diff --git a/packages/pigeon/CHANGELOG.md b/packages/pigeon/CHANGELOG.md
index 8fde584cee9..47dce97fc0b 100644
--- a/packages/pigeon/CHANGELOG.md
+++ b/packages/pigeon/CHANGELOG.md
@@ -1,5 +1,6 @@
-## NEXT
+## 19.0.0
 
+* **Breaking Change** [swift] Removes `FlutterError` in favor of `PigeonError`.
 * Updates minimum supported SDK version to Flutter 3.16/Dart 3.2.
 
 ## 18.0.1
diff --git a/packages/pigeon/README.md b/packages/pigeon/README.md
index dfa4e9847d7..2eb938092a1 100644
--- a/packages/pigeon/README.md
+++ b/packages/pigeon/README.md
@@ -53,8 +53,7 @@ should be returned via the provided callback.
 To pass custom details into `PlatformException` for error handling, 
 use `FlutterError` in your Host API. [Example](./example/README.md#HostApi_Example).
 
-To use `FlutterError` in Swift you must first extend a standard error.
-[Example](./example/README.md#AppDelegate.swift).
+For swift, use `PigeonError` instead of `FlutterError` when throwing an error. See [Example#Swift](./example/README.md#Swift) for more details.
 
 #### Objective-C and C++
 
diff --git a/packages/pigeon/example/README.md b/packages/pigeon/example/README.md
index 8e22079b47a..46e8c643b1d 100644
--- a/packages/pigeon/example/README.md
+++ b/packages/pigeon/example/README.md
@@ -115,12 +115,9 @@ Future<bool> sendMessage(String messageText) {
 ### Swift
 
 This is the code that will use the generated Swift code to receive calls from Flutter.
-packages/pigeon/example/app/ios/Runner/AppDelegate.swift
+Unlike other languages, when throwing an error, use `PigeonError` instead of `FlutterError`, as `FlutterError` does not conform to `Swift.Error`.
 <?code-excerpt "ios/Runner/AppDelegate.swift (swift-class)"?>
 ```swift
-// This extension of Error is required to do use FlutterError in any Swift code.
-extension FlutterError: Error {}
-
 private class PigeonApiImplementation: ExampleHostApi {
   func getHostLanguage() throws -> String {
     return "Swift"
@@ -128,14 +125,14 @@ private class PigeonApiImplementation: ExampleHostApi {
 
   func add(_ a: Int64, to b: Int64) throws -> Int64 {
     if a < 0 || b < 0 {
-      throw FlutterError(code: "code", message: "message", details: "details")
+      throw PigeonError(code: "code", message: "message", details: "details")
     }
     return a + b
   }
 
   func sendMessage(message: MessageData, completion: @escaping (Result<Bool, Error>) -> Void) {
     if message.code == Code.one {
-      completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+      completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
       return
     }
     completion(.success(true))
diff --git a/packages/pigeon/example/app/ios/Runner/AppDelegate.swift b/packages/pigeon/example/app/ios/Runner/AppDelegate.swift
index f259b759085..51119e23fa3 100644
--- a/packages/pigeon/example/app/ios/Runner/AppDelegate.swift
+++ b/packages/pigeon/example/app/ios/Runner/AppDelegate.swift
@@ -6,9 +6,6 @@ import Flutter
 import UIKit
 
 // #docregion swift-class
-// This extension of Error is required to do use FlutterError in any Swift code.
-extension FlutterError: Error {}
-
 private class PigeonApiImplementation: ExampleHostApi {
   func getHostLanguage() throws -> String {
     return "Swift"
@@ -16,14 +13,14 @@ private class PigeonApiImplementation: ExampleHostApi {
 
   func add(_ a: Int64, to b: Int64) throws -> Int64 {
     if a < 0 || b < 0 {
-      throw FlutterError(code: "code", message: "message", details: "details")
+      throw PigeonError(code: "code", message: "message", details: "details")
     }
     return a + b
   }
 
   func sendMessage(message: MessageData, completion: @escaping (Result<Bool, Error>) -> Void) {
     if message.code == Code.one {
-      completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+      completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
       return
     }
     completion(.success(true))
diff --git a/packages/pigeon/example/app/ios/Runner/Messages.g.swift b/packages/pigeon/example/app/ios/Runner/Messages.g.swift
index 7155583cfab..51b3cfa61de 100644
--- a/packages/pigeon/example/app/ios/Runner/Messages.g.swift
+++ b/packages/pigeon/example/app/ios/Runner/Messages.g.swift
@@ -14,11 +14,36 @@ import Foundation
   #error("Unsupported platform.")
 #endif
 
+/// Error class for passing custom error details to Dart side.
+final class PigeonError: Error {
+  let code: String
+  let message: String?
+  let details: Any?
+
+  init(code: String, message: String?, details: Any?) {
+    self.code = code
+    self.message = message
+    self.details = details
+  }
+
+  var localizedDescription: String {
+    return
+      "PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>")"
+  }
+}
+
 private func wrapResult(_ result: Any?) -> [Any?] {
   return [result]
 }
 
 private func wrapError(_ error: Any) -> [Any?] {
+  if let pigeonError = error as? PigeonError {
+    return [
+      pigeonError.code,
+      pigeonError.message,
+      pigeonError.details,
+    ]
+  }
   if let flutterError = error as? FlutterError {
     return [
       flutterError.code,
@@ -33,8 +58,8 @@ private func wrapError(_ error: Any) -> [Any?] {
   ]
 }
 
-private func createConnectionError(withChannelName channelName: String) -> FlutterError {
-  return FlutterError(
+private func createConnectionError(withChannelName channelName: String) -> PigeonError {
+  return PigeonError(
     code: "channel-error", message: "Unable to establish connection on channel: '\(channelName)'.",
     details: "")
 }
@@ -194,7 +219,7 @@ class ExampleHostApiSetup {
 /// Generated protocol from Pigeon that represents Flutter messages that can be called from Swift.
 protocol MessageFlutterApiProtocol {
   func flutterMethod(
-    aString aStringArg: String?, completion: @escaping (Result<String, FlutterError>) -> Void)
+    aString aStringArg: String?, completion: @escaping (Result<String, PigeonError>) -> Void)
 }
 class MessageFlutterApi: MessageFlutterApiProtocol {
   private let binaryMessenger: FlutterBinaryMessenger
@@ -204,7 +229,7 @@ class MessageFlutterApi: MessageFlutterApiProtocol {
     self.messageChannelSuffix = messageChannelSuffix.count > 0 ? ".\(messageChannelSuffix)" : ""
   }
   func flutterMethod(
-    aString aStringArg: String?, completion: @escaping (Result<String, FlutterError>) -> Void
+    aString aStringArg: String?, completion: @escaping (Result<String, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_example_package.MessageFlutterApi.flutterMethod\(messageChannelSuffix)"
@@ -218,11 +243,11 @@ class MessageFlutterApi: MessageFlutterApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
diff --git a/packages/pigeon/lib/generator_tools.dart b/packages/pigeon/lib/generator_tools.dart
index 98f27ad0fec..e11c448070f 100644
--- a/packages/pigeon/lib/generator_tools.dart
+++ b/packages/pigeon/lib/generator_tools.dart
@@ -13,7 +13,7 @@ import 'ast.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '18.0.1';
+const String pigeonVersion = '19.0.0';
 
 /// Prefix for all local variables in methods.
 ///
diff --git a/packages/pigeon/lib/pigeon_lib.dart b/packages/pigeon/lib/pigeon_lib.dart
index 4b3ce09574f..42da8b060f1 100644
--- a/packages/pigeon/lib/pigeon_lib.dart
+++ b/packages/pigeon/lib/pigeon_lib.dart
@@ -705,6 +705,7 @@ class SwiftGeneratorAdapter implements GeneratorAdapter {
           ? _lineReader(
               path.posix.join(options.basePath ?? '', options.copyrightHeader))
           : null,
+      errorClassName: swiftOptions.errorClassName,
     ));
     const SwiftGenerator generator = SwiftGenerator();
     generator.generate(
diff --git a/packages/pigeon/lib/swift_generator.dart b/packages/pigeon/lib/swift_generator.dart
index b644e561d5e..db5701e371b 100644
--- a/packages/pigeon/lib/swift_generator.dart
+++ b/packages/pigeon/lib/swift_generator.dart
@@ -19,16 +19,21 @@ class SwiftOptions {
   /// Creates a [SwiftOptions] object
   const SwiftOptions({
     this.copyrightHeader,
+    this.errorClassName,
   });
 
   /// A copyright header that will get prepended to generated code.
   final Iterable<String>? copyrightHeader;
 
+  /// The name of the error class used for passing custom error parameters.
+  final String? errorClassName;
+
   /// Creates a [SwiftOptions] from a Map representation where:
   /// `x = SwiftOptions.fromList(x.toMap())`.
   static SwiftOptions fromList(Map<String, Object> map) {
     return SwiftOptions(
       copyrightHeader: map['copyrightHeader'] as Iterable<String>?,
+      errorClassName: map['errorClassName'] as String?,
     );
   }
 
@@ -37,6 +42,7 @@ class SwiftOptions {
   Map<String, Object> toMap() {
     final Map<String, Object> result = <String, Object>{
       if (copyrightHeader != null) 'copyrightHeader': copyrightHeader!,
+      if (errorClassName != null) 'errorClassName': errorClassName!,
     };
     return result;
   }
@@ -316,7 +322,7 @@ class SwiftGenerator extends StructuredGenerator<SwiftOptions> {
           name: func.name,
           parameters: func.parameters,
           returnType: func.returnType,
-          errorTypeName: 'FlutterError',
+          errorTypeName: _getErrorClassName(generatorOptions),
           isAsynchronous: true,
           swiftFunction: func.swiftFunction,
           getParameterName: _getSafeArgumentName,
@@ -350,6 +356,7 @@ class SwiftGenerator extends StructuredGenerator<SwiftOptions> {
             indent, func.documentationComments, _docCommentSpec);
         _writeFlutterMethod(
           indent,
+          generatorOptions: generatorOptions,
           name: func.name,
           channelName: makeChannelName(api, func, dartPackageName),
           parameters: func.parameters,
@@ -614,10 +621,20 @@ class SwiftGenerator extends StructuredGenerator<SwiftOptions> {
     });
   }
 
-  void _writeWrapError(Indent indent) {
+  void _writeWrapError(SwiftOptions generatorOptions, Indent indent) {
     indent.newln();
     indent.write('private func wrapError(_ error: Any) -> [Any?] ');
     indent.addScoped('{', '}', () {
+      indent.write(
+          'if let pigeonError = error as? ${_getErrorClassName(generatorOptions)} ');
+      indent.addScoped('{', '}', () {
+        indent.write('return ');
+        indent.addScoped('[', ']', () {
+          indent.writeln('pigeonError.code,');
+          indent.writeln('pigeonError.message,');
+          indent.writeln('pigeonError.details,');
+        });
+      });
       indent.write('if let flutterError = error as? FlutterError ');
       indent.addScoped('{', '}', () {
         indent.write('return ');
@@ -645,13 +662,14 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
 }''');
   }
 
-  void _writeCreateConnectionError(Indent indent) {
+  void _writeCreateConnectionError(
+      SwiftOptions generatorOptions, Indent indent) {
     indent.newln();
     indent.writeScoped(
-        'private func createConnectionError(withChannelName channelName: String) -> FlutterError {',
+        'private func createConnectionError(withChannelName channelName: String) -> ${_getErrorClassName(generatorOptions)} {',
         '}', () {
       indent.writeln(
-          'return FlutterError(code: "channel-error", message: "Unable to establish connection on channel: \'\\(channelName)\'.", details: "")');
+          'return ${_getErrorClassName(generatorOptions)}(code: "channel-error", message: "Unable to establish connection on channel: \'\\(channelName)\'.", details: "")');
     });
   }
 
@@ -669,19 +687,23 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
         .whereType<AstFlutterApi>()
         .any((Api api) => api.methods.isNotEmpty);
 
+    _writePigeonError(generatorOptions, indent);
+
     if (hasHostApi) {
       _writeWrapResult(indent);
-      _writeWrapError(indent);
+      _writeWrapError(generatorOptions, indent);
     }
     if (hasFlutterApi) {
-      _writeCreateConnectionError(indent);
+      _writeCreateConnectionError(generatorOptions, indent);
     }
+
     _writeIsNullish(indent);
     _writeNilOrValue(indent);
   }
 
   void _writeFlutterMethod(
     Indent indent, {
+    required SwiftOptions generatorOptions,
     required String name,
     required String channelName,
     required List<Parameter> parameters,
@@ -693,7 +715,7 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
       name: name,
       parameters: parameters,
       returnType: returnType,
-      errorTypeName: 'FlutterError',
+      errorTypeName: _getErrorClassName(generatorOptions),
       isAsynchronous: true,
       swiftFunction: swiftFunction,
       getParameterName: _getSafeArgumentName,
@@ -735,12 +757,12 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
           indent.writeln('let message: String? = nilOrValue(listResponse[1])');
           indent.writeln('let details: String? = nilOrValue(listResponse[2])');
           indent.writeln(
-              'completion(.failure(FlutterError(code: code, message: message, details: details)))');
+              'completion(.failure(${_getErrorClassName(generatorOptions)}(code: code, message: message, details: details)))');
         }, addTrailingNewline: false);
         if (!returnType.isNullable && !returnType.isVoid) {
           indent.addScoped('else if listResponse[0] == nil {', '} ', () {
             indent.writeln(
-                'completion(.failure(FlutterError(code: "null-error", message: "Flutter api returned null value for non-null return value.", details: "")))');
+                'completion(.failure(${_getErrorClassName(generatorOptions)}(code: "null-error", message: "Flutter api returned null value for non-null return value.", details: "")))');
           }, addTrailingNewline: false);
         }
         indent.addScoped('else {', '}', () {
@@ -870,11 +892,41 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
       indent.writeln('$varChannelName.setMessageHandler(nil)');
     });
   }
+
+  void _writePigeonError(SwiftOptions generatorOptions, Indent indent) {
+    indent.newln();
+    indent.writeln(
+        '/// Error class for passing custom error details to Dart side.');
+    indent.writeScoped(
+        'final class ${_getErrorClassName(generatorOptions)}: Error {', '}',
+        () {
+      indent.writeln('let code: String');
+      indent.writeln('let message: String?');
+      indent.writeln('let details: Any?');
+      indent.newln();
+      indent.writeScoped(
+          'init(code: String, message: String?, details: Any?) {', '}', () {
+        indent.writeln('self.code = code');
+        indent.writeln('self.message = message');
+        indent.writeln('self.details = details');
+      });
+      indent.newln();
+      indent.writeScoped('var localizedDescription: String {', '}', () {
+        indent.writeScoped('return', '', () {
+          indent.writeln(
+              '"${_getErrorClassName(generatorOptions)}(code: \\(code), message: \\(message ?? "<nil>"), details: \\(details ?? "<nil>")"');
+        }, addTrailingNewline: false);
+      });
+    });
+  }
 }
 
 /// Calculates the name of the codec that will be generated for [api].
 String _getCodecName(Api api) => '${api.name}Codec';
 
+String _getErrorClassName(SwiftOptions generatorOptions) =>
+    generatorOptions.errorClassName ?? 'PigeonError';
+
 String _getArgumentName(int count, NamedType argument) =>
     argument.name.isEmpty ? 'arg$count' : argument.name;
 
diff --git a/packages/pigeon/platform_tests/test_plugin/example/ios/RunnerTests/RunnerTests.swift b/packages/pigeon/platform_tests/test_plugin/example/ios/RunnerTests/RunnerTests.swift
index e86e5c948d1..4e02aa6e24b 100644
--- a/packages/pigeon/platform_tests/test_plugin/example/ios/RunnerTests/RunnerTests.swift
+++ b/packages/pigeon/platform_tests/test_plugin/example/ios/RunnerTests/RunnerTests.swift
@@ -48,14 +48,16 @@ class RunnerTests: XCTestCase {
 }
 
 class FlutterApiFromProtocol: FlutterSmallApiProtocol {
-  func echo(string aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
-  {
+  func echo(
+    string aStringArg: String,
+    completion: @escaping (Result<String, test_plugin.PigeonError>) -> Void
+  ) {
     completion(.success(aStringArg))
   }
 
   func echo(
     _ msgArg: test_plugin.TestMessage,
-    completion: @escaping (Result<test_plugin.TestMessage, FlutterError>) -> Void
+    completion: @escaping (Result<test_plugin.TestMessage, test_plugin.PigeonError>) -> Void
   ) {
     completion(.success(msgArg))
   }
diff --git a/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift b/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift
index 717985e7a4b..c54100d2db4 100644
--- a/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift
+++ b/packages/pigeon/platform_tests/test_plugin/ios/Classes/CoreTests.gen.swift
@@ -15,11 +15,36 @@ import Foundation
   #error("Unsupported platform.")
 #endif
 
+/// Error class for passing custom error details to Dart side.
+final class PigeonError: Error {
+  let code: String
+  let message: String?
+  let details: Any?
+
+  init(code: String, message: String?, details: Any?) {
+    self.code = code
+    self.message = message
+    self.details = details
+  }
+
+  var localizedDescription: String {
+    return
+      "PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>")"
+  }
+}
+
 private func wrapResult(_ result: Any?) -> [Any?] {
   return [result]
 }
 
 private func wrapError(_ error: Any) -> [Any?] {
+  if let pigeonError = error as? PigeonError {
+    return [
+      pigeonError.code,
+      pigeonError.message,
+      pigeonError.details,
+    ]
+  }
   if let flutterError = error as? FlutterError {
     return [
       flutterError.code,
@@ -34,8 +59,8 @@ private func wrapError(_ error: Any) -> [Any?] {
   ]
 }
 
-private func createConnectionError(withChannelName channelName: String) -> FlutterError {
-  return FlutterError(
+private func createConnectionError(withChannelName channelName: String) -> PigeonError {
+  return PigeonError(
     code: "channel-error", message: "Unable to establish connection on channel: '\(channelName)'.",
     details: "")
 }
@@ -2438,86 +2463,85 @@ class FlutterIntegrationCoreApiCodec: FlutterStandardMessageCodec {
 protocol FlutterIntegrationCoreApiProtocol {
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic calling.
-  func noop(completion: @escaping (Result<Void, FlutterError>) -> Void)
+  func noop(completion: @escaping (Result<Void, PigeonError>) -> Void)
   /// Responds with an error from an async function returning a value.
-  func throwError(completion: @escaping (Result<Any?, FlutterError>) -> Void)
+  func throwError(completion: @escaping (Result<Any?, PigeonError>) -> Void)
   /// Responds with an error from an async void function.
-  func throwErrorFromVoid(completion: @escaping (Result<Void, FlutterError>) -> Void)
+  func throwErrorFromVoid(completion: @escaping (Result<Void, PigeonError>) -> Void)
   /// Returns the passed object, to test serialization and deserialization.
   func echo(
-    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, FlutterError>) -> Void)
+    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, PigeonError>) -> Void)
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypes?,
-    completion: @escaping (Result<AllNullableTypes?, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypes?, PigeonError>) -> Void)
   /// Returns passed in arguments of multiple types.
   ///
   /// Tests multiple-arity FlutterApi handling.
   func sendMultipleNullableTypes(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypes, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypes, PigeonError>) -> Void)
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypesWithoutRecursion?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, PigeonError>) -> Void)
   /// Returns passed in arguments of multiple types.
   ///
   /// Tests multiple-arity FlutterApi handling.
   func sendMultipleNullableTypesWithoutRecursion(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion, PigeonError>) -> Void)
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, FlutterError>) -> Void)
+  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, PigeonError>) -> Void)
   /// Returns the passed int, to test serialization and deserialization.
-  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, FlutterError>) -> Void)
+  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, PigeonError>) -> Void)
   /// Returns the passed double, to test serialization and deserialization.
-  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, FlutterError>) -> Void)
+  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, PigeonError>) -> Void)
   /// Returns the passed string, to test serialization and deserialization.
-  func echo(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echo(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
   /// Returns the passed byte list, to test serialization and deserialization.
   func echo(
     _ listArg: FlutterStandardTypedData,
-    completion: @escaping (Result<FlutterStandardTypedData, FlutterError>) -> Void)
+    completion: @escaping (Result<FlutterStandardTypedData, PigeonError>) -> Void)
   /// Returns the passed list, to test serialization and deserialization.
-  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], FlutterError>) -> Void)
+  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], PigeonError>) -> Void)
   /// Returns the passed map, to test serialization and deserialization.
   func echo(
-    _ aMapArg: [String?: Any?],
-    completion: @escaping (Result<[String?: Any?], FlutterError>) -> Void)
+    _ aMapArg: [String?: Any?], completion: @escaping (Result<[String?: Any?], PigeonError>) -> Void
+  )
   /// Returns the passed enum to test serialization and deserialization.
-  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, FlutterError>) -> Void)
+  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, PigeonError>) -> Void)
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, FlutterError>) -> Void)
+  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, PigeonError>) -> Void)
   /// Returns the passed int, to test serialization and deserialization.
-  func echoNullable(
-    _ anIntArg: Int64?, completion: @escaping (Result<Int64?, FlutterError>) -> Void)
+  func echoNullable(_ anIntArg: Int64?, completion: @escaping (Result<Int64?, PigeonError>) -> Void)
   /// Returns the passed double, to test serialization and deserialization.
   func echoNullable(
-    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, FlutterError>) -> Void)
+    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, PigeonError>) -> Void)
   /// Returns the passed string, to test serialization and deserialization.
   func echoNullable(
-    _ aStringArg: String?, completion: @escaping (Result<String?, FlutterError>) -> Void)
+    _ aStringArg: String?, completion: @escaping (Result<String?, PigeonError>) -> Void)
   /// Returns the passed byte list, to test serialization and deserialization.
   func echoNullable(
     _ listArg: FlutterStandardTypedData?,
-    completion: @escaping (Result<FlutterStandardTypedData?, FlutterError>) -> Void)
+    completion: @escaping (Result<FlutterStandardTypedData?, PigeonError>) -> Void)
   /// Returns the passed list, to test serialization and deserialization.
   func echoNullable(
-    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, FlutterError>) -> Void)
+    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, PigeonError>) -> Void)
   /// Returns the passed map, to test serialization and deserialization.
   func echoNullable(
     _ aMapArg: [String?: Any?]?,
-    completion: @escaping (Result<[String?: Any?]?, FlutterError>) -> Void)
+    completion: @escaping (Result<[String?: Any?]?, PigeonError>) -> Void)
   /// Returns the passed enum to test serialization and deserialization.
   func echoNullable(
-    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, FlutterError>) -> Void)
+    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, PigeonError>) -> Void)
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic asynchronous calling.
-  func noopAsync(completion: @escaping (Result<Void, FlutterError>) -> Void)
+  func noopAsync(completion: @escaping (Result<Void, PigeonError>) -> Void)
   /// Returns the passed in generic Object asynchronously.
-  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
 }
 class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   private let binaryMessenger: FlutterBinaryMessenger
@@ -2531,7 +2555,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic calling.
-  func noop(completion: @escaping (Result<Void, FlutterError>) -> Void) {
+  func noop(completion: @escaping (Result<Void, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.noop\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2545,14 +2569,14 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         completion(.success(Void()))
       }
     }
   }
   /// Responds with an error from an async function returning a value.
-  func throwError(completion: @escaping (Result<Any?, FlutterError>) -> Void) {
+  func throwError(completion: @escaping (Result<Any?, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.throwError\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2566,7 +2590,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Any? = listResponse[0]
         completion(.success(result))
@@ -2574,7 +2598,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Responds with an error from an async void function.
-  func throwErrorFromVoid(completion: @escaping (Result<Void, FlutterError>) -> Void) {
+  func throwErrorFromVoid(completion: @escaping (Result<Void, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.throwErrorFromVoid\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2588,7 +2612,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         completion(.success(Void()))
       }
@@ -2596,7 +2620,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed object, to test serialization and deserialization.
   func echo(
-    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, FlutterError>) -> Void
+    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAllTypes\(messageChannelSuffix)"
@@ -2611,11 +2635,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2627,7 +2651,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypes?,
-    completion: @escaping (Result<AllNullableTypes?, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypes?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAllNullableTypes\(messageChannelSuffix)"
@@ -2642,7 +2666,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: AllNullableTypes? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -2655,7 +2679,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   func sendMultipleNullableTypes(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypes, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypes, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.sendMultipleNullableTypes\(messageChannelSuffix)"
@@ -2671,11 +2695,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2687,7 +2711,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypesWithoutRecursion?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAllNullableTypesWithoutRecursion\(messageChannelSuffix)"
@@ -2702,7 +2726,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: AllNullableTypesWithoutRecursion? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -2715,7 +2739,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   func sendMultipleNullableTypesWithoutRecursion(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.sendMultipleNullableTypesWithoutRecursion\(messageChannelSuffix)"
@@ -2731,11 +2755,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2745,7 +2769,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, FlutterError>) -> Void) {
+  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoBool\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2759,11 +2783,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2773,7 +2797,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed int, to test serialization and deserialization.
-  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, FlutterError>) -> Void) {
+  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoInt\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2787,11 +2811,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2802,7 +2826,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed double, to test serialization and deserialization.
-  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, FlutterError>) -> Void) {
+  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoDouble\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2816,11 +2840,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2830,7 +2854,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed string, to test serialization and deserialization.
-  func echo(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void) {
+  func echo(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoString\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2844,11 +2868,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2860,7 +2884,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed byte list, to test serialization and deserialization.
   func echo(
     _ listArg: FlutterStandardTypedData,
-    completion: @escaping (Result<FlutterStandardTypedData, FlutterError>) -> Void
+    completion: @escaping (Result<FlutterStandardTypedData, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoUint8List\(messageChannelSuffix)"
@@ -2875,11 +2899,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2889,7 +2913,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed list, to test serialization and deserialization.
-  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], FlutterError>) -> Void) {
+  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoList\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2903,11 +2927,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2918,8 +2942,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed map, to test serialization and deserialization.
   func echo(
-    _ aMapArg: [String?: Any?],
-    completion: @escaping (Result<[String?: Any?], FlutterError>) -> Void
+    _ aMapArg: [String?: Any?], completion: @escaping (Result<[String?: Any?], PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoMap\(messageChannelSuffix)"
@@ -2934,11 +2957,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2948,7 +2971,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed enum to test serialization and deserialization.
-  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, FlutterError>) -> Void) {
+  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoEnum\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2962,11 +2985,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2976,8 +2999,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, FlutterError>) -> Void)
-  {
+  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableBool\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2991,7 +3013,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Bool? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -2999,9 +3021,8 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed int, to test serialization and deserialization.
-  func echoNullable(
-    _ anIntArg: Int64?, completion: @escaping (Result<Int64?, FlutterError>) -> Void
-  ) {
+  func echoNullable(_ anIntArg: Int64?, completion: @escaping (Result<Int64?, PigeonError>) -> Void)
+  {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableInt\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -3015,7 +3036,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Int64? =
           isNullish(listResponse[0])
@@ -3028,7 +3049,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed double, to test serialization and deserialization.
   func echoNullable(
-    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, FlutterError>) -> Void
+    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableDouble\(messageChannelSuffix)"
@@ -3043,7 +3064,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Double? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3052,7 +3073,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed string, to test serialization and deserialization.
   func echoNullable(
-    _ aStringArg: String?, completion: @escaping (Result<String?, FlutterError>) -> Void
+    _ aStringArg: String?, completion: @escaping (Result<String?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableString\(messageChannelSuffix)"
@@ -3067,7 +3088,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: String? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3077,7 +3098,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed byte list, to test serialization and deserialization.
   func echoNullable(
     _ listArg: FlutterStandardTypedData?,
-    completion: @escaping (Result<FlutterStandardTypedData?, FlutterError>) -> Void
+    completion: @escaping (Result<FlutterStandardTypedData?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableUint8List\(messageChannelSuffix)"
@@ -3092,7 +3113,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: FlutterStandardTypedData? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3101,7 +3122,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed list, to test serialization and deserialization.
   func echoNullable(
-    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, FlutterError>) -> Void
+    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableList\(messageChannelSuffix)"
@@ -3116,7 +3137,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: [Any?]? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3126,7 +3147,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed map, to test serialization and deserialization.
   func echoNullable(
     _ aMapArg: [String?: Any?]?,
-    completion: @escaping (Result<[String?: Any?]?, FlutterError>) -> Void
+    completion: @escaping (Result<[String?: Any?]?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableMap\(messageChannelSuffix)"
@@ -3141,7 +3162,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: [String?: Any?]? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3150,7 +3171,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed enum to test serialization and deserialization.
   func echoNullable(
-    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, FlutterError>) -> Void
+    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableEnum\(messageChannelSuffix)"
@@ -3165,7 +3186,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: AnEnum? =
           isNullish(listResponse[0]) ? nil : AnEnum(rawValue: listResponse[0] as! Int)!
@@ -3175,7 +3196,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic asynchronous calling.
-  func noopAsync(completion: @escaping (Result<Void, FlutterError>) -> Void) {
+  func noopAsync(completion: @escaping (Result<Void, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.noopAsync\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -3189,14 +3210,14 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         completion(.success(Void()))
       }
     }
   }
   /// Returns the passed in generic Object asynchronously.
-  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
   {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAsyncString\(messageChannelSuffix)"
@@ -3211,11 +3232,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -3351,9 +3372,8 @@ class FlutterSmallApiCodec: FlutterStandardMessageCodec {
 ///
 /// Generated protocol from Pigeon that represents Flutter messages that can be called from Swift.
 protocol FlutterSmallApiProtocol {
-  func echo(
-    _ msgArg: TestMessage, completion: @escaping (Result<TestMessage, FlutterError>) -> Void)
-  func echo(string aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echo(_ msgArg: TestMessage, completion: @escaping (Result<TestMessage, PigeonError>) -> Void)
+  func echo(string aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
 }
 class FlutterSmallApi: FlutterSmallApiProtocol {
   private let binaryMessenger: FlutterBinaryMessenger
@@ -3365,9 +3385,8 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
   var codec: FlutterStandardMessageCodec {
     return FlutterSmallApiCodec.shared
   }
-  func echo(
-    _ msgArg: TestMessage, completion: @escaping (Result<TestMessage, FlutterError>) -> Void
-  ) {
+  func echo(_ msgArg: TestMessage, completion: @escaping (Result<TestMessage, PigeonError>) -> Void)
+  {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterSmallApi.echoWrappedList\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -3381,11 +3400,11 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -3394,7 +3413,7 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
       }
     }
   }
-  func echo(string aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echo(string aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
   {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterSmallApi.echoString\(messageChannelSuffix)"
@@ -3409,11 +3428,11 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
diff --git a/packages/pigeon/platform_tests/test_plugin/ios/Classes/TestPlugin.swift b/packages/pigeon/platform_tests/test_plugin/ios/Classes/TestPlugin.swift
index a00affe7040..36e6a445b53 100644
--- a/packages/pigeon/platform_tests/test_plugin/ios/Classes/TestPlugin.swift
+++ b/packages/pigeon/platform_tests/test_plugin/ios/Classes/TestPlugin.swift
@@ -5,8 +5,6 @@
 import Flutter
 import UIKit
 
-extension FlutterError: Error {}
-
 /// This plugin handles the native side of the integration tests in
 /// example/integration_test/.
 public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
@@ -50,15 +48,15 @@ public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
   }
 
   func throwError() throws -> Any? {
-    throw FlutterError(code: "code", message: "message", details: "details")
+    throw PigeonError(code: "code", message: "message", details: "details")
   }
 
   func throwErrorFromVoid() throws {
-    throw FlutterError(code: "code", message: "message", details: "details")
+    throw PigeonError(code: "code", message: "message", details: "details")
   }
 
   func throwFlutterError() throws -> Any? {
-    throw FlutterError(code: "code", message: "message", details: "details")
+    throw PigeonError(code: "code", message: "message", details: "details")
   }
 
   func echo(_ anInt: Int64) -> Int64 {
@@ -186,15 +184,15 @@ public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
   }
 
   func throwAsyncError(completion: @escaping (Result<Any?, Error>) -> Void) {
-    completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+    completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
   }
 
   func throwAsyncErrorFromVoid(completion: @escaping (Result<Void, Error>) -> Void) {
-    completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+    completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
   }
 
   func throwAsyncFlutterError(completion: @escaping (Result<Any?, Error>) -> Void) {
-    completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+    completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
   }
 
   func echoAsync(_ everything: AllTypes, completion: @escaping (Result<AllTypes, Error>) -> Void) {
@@ -623,7 +621,7 @@ public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
             } else {
               completion(
                 .failure(
-                  FlutterError(
+                  PigeonError(
                     code: "",
                     message: "Multi-instance responses were not matching: \(resOne), \(resTwo)",
                     details: nil)))
diff --git a/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift b/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift
index 717985e7a4b..c54100d2db4 100644
--- a/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift
+++ b/packages/pigeon/platform_tests/test_plugin/macos/Classes/CoreTests.gen.swift
@@ -15,11 +15,36 @@ import Foundation
   #error("Unsupported platform.")
 #endif
 
+/// Error class for passing custom error details to Dart side.
+final class PigeonError: Error {
+  let code: String
+  let message: String?
+  let details: Any?
+
+  init(code: String, message: String?, details: Any?) {
+    self.code = code
+    self.message = message
+    self.details = details
+  }
+
+  var localizedDescription: String {
+    return
+      "PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>")"
+  }
+}
+
 private func wrapResult(_ result: Any?) -> [Any?] {
   return [result]
 }
 
 private func wrapError(_ error: Any) -> [Any?] {
+  if let pigeonError = error as? PigeonError {
+    return [
+      pigeonError.code,
+      pigeonError.message,
+      pigeonError.details,
+    ]
+  }
   if let flutterError = error as? FlutterError {
     return [
       flutterError.code,
@@ -34,8 +59,8 @@ private func wrapError(_ error: Any) -> [Any?] {
   ]
 }
 
-private func createConnectionError(withChannelName channelName: String) -> FlutterError {
-  return FlutterError(
+private func createConnectionError(withChannelName channelName: String) -> PigeonError {
+  return PigeonError(
     code: "channel-error", message: "Unable to establish connection on channel: '\(channelName)'.",
     details: "")
 }
@@ -2438,86 +2463,85 @@ class FlutterIntegrationCoreApiCodec: FlutterStandardMessageCodec {
 protocol FlutterIntegrationCoreApiProtocol {
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic calling.
-  func noop(completion: @escaping (Result<Void, FlutterError>) -> Void)
+  func noop(completion: @escaping (Result<Void, PigeonError>) -> Void)
   /// Responds with an error from an async function returning a value.
-  func throwError(completion: @escaping (Result<Any?, FlutterError>) -> Void)
+  func throwError(completion: @escaping (Result<Any?, PigeonError>) -> Void)
   /// Responds with an error from an async void function.
-  func throwErrorFromVoid(completion: @escaping (Result<Void, FlutterError>) -> Void)
+  func throwErrorFromVoid(completion: @escaping (Result<Void, PigeonError>) -> Void)
   /// Returns the passed object, to test serialization and deserialization.
   func echo(
-    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, FlutterError>) -> Void)
+    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, PigeonError>) -> Void)
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypes?,
-    completion: @escaping (Result<AllNullableTypes?, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypes?, PigeonError>) -> Void)
   /// Returns passed in arguments of multiple types.
   ///
   /// Tests multiple-arity FlutterApi handling.
   func sendMultipleNullableTypes(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypes, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypes, PigeonError>) -> Void)
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypesWithoutRecursion?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, PigeonError>) -> Void)
   /// Returns passed in arguments of multiple types.
   ///
   /// Tests multiple-arity FlutterApi handling.
   func sendMultipleNullableTypesWithoutRecursion(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion, FlutterError>) -> Void)
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion, PigeonError>) -> Void)
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, FlutterError>) -> Void)
+  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, PigeonError>) -> Void)
   /// Returns the passed int, to test serialization and deserialization.
-  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, FlutterError>) -> Void)
+  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, PigeonError>) -> Void)
   /// Returns the passed double, to test serialization and deserialization.
-  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, FlutterError>) -> Void)
+  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, PigeonError>) -> Void)
   /// Returns the passed string, to test serialization and deserialization.
-  func echo(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echo(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
   /// Returns the passed byte list, to test serialization and deserialization.
   func echo(
     _ listArg: FlutterStandardTypedData,
-    completion: @escaping (Result<FlutterStandardTypedData, FlutterError>) -> Void)
+    completion: @escaping (Result<FlutterStandardTypedData, PigeonError>) -> Void)
   /// Returns the passed list, to test serialization and deserialization.
-  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], FlutterError>) -> Void)
+  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], PigeonError>) -> Void)
   /// Returns the passed map, to test serialization and deserialization.
   func echo(
-    _ aMapArg: [String?: Any?],
-    completion: @escaping (Result<[String?: Any?], FlutterError>) -> Void)
+    _ aMapArg: [String?: Any?], completion: @escaping (Result<[String?: Any?], PigeonError>) -> Void
+  )
   /// Returns the passed enum to test serialization and deserialization.
-  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, FlutterError>) -> Void)
+  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, PigeonError>) -> Void)
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, FlutterError>) -> Void)
+  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, PigeonError>) -> Void)
   /// Returns the passed int, to test serialization and deserialization.
-  func echoNullable(
-    _ anIntArg: Int64?, completion: @escaping (Result<Int64?, FlutterError>) -> Void)
+  func echoNullable(_ anIntArg: Int64?, completion: @escaping (Result<Int64?, PigeonError>) -> Void)
   /// Returns the passed double, to test serialization and deserialization.
   func echoNullable(
-    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, FlutterError>) -> Void)
+    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, PigeonError>) -> Void)
   /// Returns the passed string, to test serialization and deserialization.
   func echoNullable(
-    _ aStringArg: String?, completion: @escaping (Result<String?, FlutterError>) -> Void)
+    _ aStringArg: String?, completion: @escaping (Result<String?, PigeonError>) -> Void)
   /// Returns the passed byte list, to test serialization and deserialization.
   func echoNullable(
     _ listArg: FlutterStandardTypedData?,
-    completion: @escaping (Result<FlutterStandardTypedData?, FlutterError>) -> Void)
+    completion: @escaping (Result<FlutterStandardTypedData?, PigeonError>) -> Void)
   /// Returns the passed list, to test serialization and deserialization.
   func echoNullable(
-    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, FlutterError>) -> Void)
+    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, PigeonError>) -> Void)
   /// Returns the passed map, to test serialization and deserialization.
   func echoNullable(
     _ aMapArg: [String?: Any?]?,
-    completion: @escaping (Result<[String?: Any?]?, FlutterError>) -> Void)
+    completion: @escaping (Result<[String?: Any?]?, PigeonError>) -> Void)
   /// Returns the passed enum to test serialization and deserialization.
   func echoNullable(
-    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, FlutterError>) -> Void)
+    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, PigeonError>) -> Void)
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic asynchronous calling.
-  func noopAsync(completion: @escaping (Result<Void, FlutterError>) -> Void)
+  func noopAsync(completion: @escaping (Result<Void, PigeonError>) -> Void)
   /// Returns the passed in generic Object asynchronously.
-  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
 }
 class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   private let binaryMessenger: FlutterBinaryMessenger
@@ -2531,7 +2555,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic calling.
-  func noop(completion: @escaping (Result<Void, FlutterError>) -> Void) {
+  func noop(completion: @escaping (Result<Void, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.noop\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2545,14 +2569,14 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         completion(.success(Void()))
       }
     }
   }
   /// Responds with an error from an async function returning a value.
-  func throwError(completion: @escaping (Result<Any?, FlutterError>) -> Void) {
+  func throwError(completion: @escaping (Result<Any?, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.throwError\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2566,7 +2590,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Any? = listResponse[0]
         completion(.success(result))
@@ -2574,7 +2598,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Responds with an error from an async void function.
-  func throwErrorFromVoid(completion: @escaping (Result<Void, FlutterError>) -> Void) {
+  func throwErrorFromVoid(completion: @escaping (Result<Void, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.throwErrorFromVoid\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2588,7 +2612,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         completion(.success(Void()))
       }
@@ -2596,7 +2620,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed object, to test serialization and deserialization.
   func echo(
-    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, FlutterError>) -> Void
+    _ everythingArg: AllTypes, completion: @escaping (Result<AllTypes, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAllTypes\(messageChannelSuffix)"
@@ -2611,11 +2635,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2627,7 +2651,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypes?,
-    completion: @escaping (Result<AllNullableTypes?, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypes?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAllNullableTypes\(messageChannelSuffix)"
@@ -2642,7 +2666,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: AllNullableTypes? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -2655,7 +2679,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   func sendMultipleNullableTypes(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypes, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypes, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.sendMultipleNullableTypes\(messageChannelSuffix)"
@@ -2671,11 +2695,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2687,7 +2711,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed object, to test serialization and deserialization.
   func echoNullable(
     _ everythingArg: AllNullableTypesWithoutRecursion?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAllNullableTypesWithoutRecursion\(messageChannelSuffix)"
@@ -2702,7 +2726,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: AllNullableTypesWithoutRecursion? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -2715,7 +2739,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   func sendMultipleNullableTypesWithoutRecursion(
     aBool aNullableBoolArg: Bool?, anInt aNullableIntArg: Int64?,
     aString aNullableStringArg: String?,
-    completion: @escaping (Result<AllNullableTypesWithoutRecursion, FlutterError>) -> Void
+    completion: @escaping (Result<AllNullableTypesWithoutRecursion, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.sendMultipleNullableTypesWithoutRecursion\(messageChannelSuffix)"
@@ -2731,11 +2755,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2745,7 +2769,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, FlutterError>) -> Void) {
+  func echo(_ aBoolArg: Bool, completion: @escaping (Result<Bool, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoBool\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2759,11 +2783,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2773,7 +2797,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed int, to test serialization and deserialization.
-  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, FlutterError>) -> Void) {
+  func echo(_ anIntArg: Int64, completion: @escaping (Result<Int64, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoInt\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2787,11 +2811,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2802,7 +2826,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed double, to test serialization and deserialization.
-  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, FlutterError>) -> Void) {
+  func echo(_ aDoubleArg: Double, completion: @escaping (Result<Double, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoDouble\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2816,11 +2840,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2830,7 +2854,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed string, to test serialization and deserialization.
-  func echo(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void) {
+  func echo(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoString\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2844,11 +2868,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2860,7 +2884,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed byte list, to test serialization and deserialization.
   func echo(
     _ listArg: FlutterStandardTypedData,
-    completion: @escaping (Result<FlutterStandardTypedData, FlutterError>) -> Void
+    completion: @escaping (Result<FlutterStandardTypedData, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoUint8List\(messageChannelSuffix)"
@@ -2875,11 +2899,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2889,7 +2913,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed list, to test serialization and deserialization.
-  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], FlutterError>) -> Void) {
+  func echo(_ listArg: [Any?], completion: @escaping (Result<[Any?], PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoList\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2903,11 +2927,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2918,8 +2942,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed map, to test serialization and deserialization.
   func echo(
-    _ aMapArg: [String?: Any?],
-    completion: @escaping (Result<[String?: Any?], FlutterError>) -> Void
+    _ aMapArg: [String?: Any?], completion: @escaping (Result<[String?: Any?], PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoMap\(messageChannelSuffix)"
@@ -2934,11 +2957,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2948,7 +2971,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed enum to test serialization and deserialization.
-  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, FlutterError>) -> Void) {
+  func echo(_ anEnumArg: AnEnum, completion: @escaping (Result<AnEnum, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoEnum\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2962,11 +2985,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -2976,8 +2999,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed boolean, to test serialization and deserialization.
-  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, FlutterError>) -> Void)
-  {
+  func echoNullable(_ aBoolArg: Bool?, completion: @escaping (Result<Bool?, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableBool\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -2991,7 +3013,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Bool? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -2999,9 +3021,8 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
     }
   }
   /// Returns the passed int, to test serialization and deserialization.
-  func echoNullable(
-    _ anIntArg: Int64?, completion: @escaping (Result<Int64?, FlutterError>) -> Void
-  ) {
+  func echoNullable(_ anIntArg: Int64?, completion: @escaping (Result<Int64?, PigeonError>) -> Void)
+  {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableInt\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -3015,7 +3036,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Int64? =
           isNullish(listResponse[0])
@@ -3028,7 +3049,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed double, to test serialization and deserialization.
   func echoNullable(
-    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, FlutterError>) -> Void
+    _ aDoubleArg: Double?, completion: @escaping (Result<Double?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableDouble\(messageChannelSuffix)"
@@ -3043,7 +3064,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: Double? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3052,7 +3073,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed string, to test serialization and deserialization.
   func echoNullable(
-    _ aStringArg: String?, completion: @escaping (Result<String?, FlutterError>) -> Void
+    _ aStringArg: String?, completion: @escaping (Result<String?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableString\(messageChannelSuffix)"
@@ -3067,7 +3088,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: String? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3077,7 +3098,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed byte list, to test serialization and deserialization.
   func echoNullable(
     _ listArg: FlutterStandardTypedData?,
-    completion: @escaping (Result<FlutterStandardTypedData?, FlutterError>) -> Void
+    completion: @escaping (Result<FlutterStandardTypedData?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableUint8List\(messageChannelSuffix)"
@@ -3092,7 +3113,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: FlutterStandardTypedData? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3101,7 +3122,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed list, to test serialization and deserialization.
   func echoNullable(
-    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, FlutterError>) -> Void
+    _ listArg: [Any?]?, completion: @escaping (Result<[Any?]?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableList\(messageChannelSuffix)"
@@ -3116,7 +3137,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: [Any?]? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3126,7 +3147,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   /// Returns the passed map, to test serialization and deserialization.
   func echoNullable(
     _ aMapArg: [String?: Any?]?,
-    completion: @escaping (Result<[String?: Any?]?, FlutterError>) -> Void
+    completion: @escaping (Result<[String?: Any?]?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableMap\(messageChannelSuffix)"
@@ -3141,7 +3162,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: [String?: Any?]? = nilOrValue(listResponse[0])
         completion(.success(result))
@@ -3150,7 +3171,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// Returns the passed enum to test serialization and deserialization.
   func echoNullable(
-    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, FlutterError>) -> Void
+    _ anEnumArg: AnEnum?, completion: @escaping (Result<AnEnum?, PigeonError>) -> Void
   ) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoNullableEnum\(messageChannelSuffix)"
@@ -3165,7 +3186,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         let result: AnEnum? =
           isNullish(listResponse[0]) ? nil : AnEnum(rawValue: listResponse[0] as! Int)!
@@ -3175,7 +3196,7 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
   }
   /// A no-op function taking no arguments and returning no value, to sanity
   /// test basic asynchronous calling.
-  func noopAsync(completion: @escaping (Result<Void, FlutterError>) -> Void) {
+  func noopAsync(completion: @escaping (Result<Void, PigeonError>) -> Void) {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.noopAsync\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -3189,14 +3210,14 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else {
         completion(.success(Void()))
       }
     }
   }
   /// Returns the passed in generic Object asynchronously.
-  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echoAsync(_ aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
   {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterIntegrationCoreApi.echoAsyncString\(messageChannelSuffix)"
@@ -3211,11 +3232,11 @@ class FlutterIntegrationCoreApi: FlutterIntegrationCoreApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -3351,9 +3372,8 @@ class FlutterSmallApiCodec: FlutterStandardMessageCodec {
 ///
 /// Generated protocol from Pigeon that represents Flutter messages that can be called from Swift.
 protocol FlutterSmallApiProtocol {
-  func echo(
-    _ msgArg: TestMessage, completion: @escaping (Result<TestMessage, FlutterError>) -> Void)
-  func echo(string aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echo(_ msgArg: TestMessage, completion: @escaping (Result<TestMessage, PigeonError>) -> Void)
+  func echo(string aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
 }
 class FlutterSmallApi: FlutterSmallApiProtocol {
   private let binaryMessenger: FlutterBinaryMessenger
@@ -3365,9 +3385,8 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
   var codec: FlutterStandardMessageCodec {
     return FlutterSmallApiCodec.shared
   }
-  func echo(
-    _ msgArg: TestMessage, completion: @escaping (Result<TestMessage, FlutterError>) -> Void
-  ) {
+  func echo(_ msgArg: TestMessage, completion: @escaping (Result<TestMessage, PigeonError>) -> Void)
+  {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterSmallApi.echoWrappedList\(messageChannelSuffix)"
     let channel = FlutterBasicMessageChannel(
@@ -3381,11 +3400,11 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
@@ -3394,7 +3413,7 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
       }
     }
   }
-  func echo(string aStringArg: String, completion: @escaping (Result<String, FlutterError>) -> Void)
+  func echo(string aStringArg: String, completion: @escaping (Result<String, PigeonError>) -> Void)
   {
     let channelName: String =
       "dev.flutter.pigeon.pigeon_integration_tests.FlutterSmallApi.echoString\(messageChannelSuffix)"
@@ -3409,11 +3428,11 @@ class FlutterSmallApi: FlutterSmallApiProtocol {
         let code: String = listResponse[0] as! String
         let message: String? = nilOrValue(listResponse[1])
         let details: String? = nilOrValue(listResponse[2])
-        completion(.failure(FlutterError(code: code, message: message, details: details)))
+        completion(.failure(PigeonError(code: code, message: message, details: details)))
       } else if listResponse[0] == nil {
         completion(
           .failure(
-            FlutterError(
+            PigeonError(
               code: "null-error",
               message: "Flutter api returned null value for non-null return value.", details: "")))
       } else {
diff --git a/packages/pigeon/platform_tests/test_plugin/macos/Classes/TestPlugin.swift b/packages/pigeon/platform_tests/test_plugin/macos/Classes/TestPlugin.swift
index 2c415135bcc..5a649736641 100644
--- a/packages/pigeon/platform_tests/test_plugin/macos/Classes/TestPlugin.swift
+++ b/packages/pigeon/platform_tests/test_plugin/macos/Classes/TestPlugin.swift
@@ -5,8 +5,6 @@
 import Cocoa
 import FlutterMacOS
 
-extension FlutterError: Error {}
-
 /// This plugin handles the native side of the integration tests in
 /// example/integration_test/.
 public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
@@ -49,15 +47,15 @@ public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
   }
 
   func throwError() throws -> Any? {
-    throw FlutterError(code: "code", message: "message", details: "details")
+    throw PigeonError(code: "code", message: "message", details: "details")
   }
 
   func throwErrorFromVoid() throws {
-    throw FlutterError(code: "code", message: "message", details: "details")
+    throw PigeonError(code: "code", message: "message", details: "details")
   }
 
   func throwFlutterError() throws -> Any? {
-    throw FlutterError(code: "code", message: "message", details: "details")
+    throw PigeonError(code: "code", message: "message", details: "details")
   }
 
   func echo(_ anInt: Int64) -> Int64 {
@@ -185,15 +183,15 @@ public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
   }
 
   func throwAsyncError(completion: @escaping (Result<Any?, Error>) -> Void) {
-    completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+    completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
   }
 
   func throwAsyncErrorFromVoid(completion: @escaping (Result<Void, Error>) -> Void) {
-    completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+    completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
   }
 
   func throwAsyncFlutterError(completion: @escaping (Result<Any?, Error>) -> Void) {
-    completion(.failure(FlutterError(code: "code", message: "message", details: "details")))
+    completion(.failure(PigeonError(code: "code", message: "message", details: "details")))
   }
 
   func echoAsync(_ everything: AllTypes, completion: @escaping (Result<AllTypes, Error>) -> Void) {
@@ -622,7 +620,7 @@ public class TestPlugin: NSObject, FlutterPlugin, HostIntegrationCoreApi {
             } else {
               completion(
                 .failure(
-                  FlutterError(
+                  PigeonError(
                     code: "",
                     message: "Multi-instance responses were not matching: \(resOne), \(resTwo)",
                     details: nil)))
diff --git a/packages/pigeon/pubspec.yaml b/packages/pigeon/pubspec.yaml
index e727afd0468..f3ceac84cba 100644
--- a/packages/pigeon/pubspec.yaml
+++ b/packages/pigeon/pubspec.yaml
@@ -2,7 +2,7 @@ name: pigeon
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 repository: https://github.com/flutter/packages/tree/main/packages/pigeon
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+pigeon%22
-version: 18.0.1 # This must match the version in lib/generator_tools.dart
+version: 19.0.0 # This must match the version in lib/generator_tools.dart
 
 environment:
   sdk: ^3.2.0
diff --git a/packages/pigeon/test/swift_generator_test.dart b/packages/pigeon/test/swift_generator_test.dart
index 8fb544bbedb..780736c03b5 100644
--- a/packages/pigeon/test/swift_generator_test.dart
+++ b/packages/pigeon/test/swift_generator_test.dart
@@ -395,7 +395,7 @@ void main() {
     );
     final String code = sink.toString();
     expect(code,
-        contains('completion: @escaping (Result<Void, FlutterError>) -> Void'));
+        contains('completion: @escaping (Result<Void, PigeonError>) -> Void'));
     expect(code, contains('completion(.success(Void()))'));
     expect(code, isNot(contains('if (')));
   });
@@ -477,7 +477,7 @@ void main() {
     expect(
         code,
         contains(
-            'func doSomething(completion: @escaping (Result<Output, FlutterError>) -> Void)'));
+            'func doSomething(completion: @escaping (Result<Output, PigeonError>) -> Void)'));
     expect(code, contains('channel.sendMessage(nil'));
     expect(code, isNot(contains('if (')));
   });
@@ -964,7 +964,7 @@ void main() {
     expect(
         code,
         contains(
-            'func doit(completion: @escaping (Result<[Int64?], FlutterError>) -> Void)'));
+            'func doit(completion: @escaping (Result<[Int64?], PigeonError>) -> Void)'));
     expect(code, contains('let result = listResponse[0] as! [Int64?]'));
     expect(code, contains('completion(.success(result))'));
   });
@@ -1052,7 +1052,7 @@ void main() {
     expect(
         code,
         contains(
-            'func add(x xArg: Int64, y yArg: Int64, completion: @escaping (Result<Int64, FlutterError>) -> Void)'));
+            'func add(x xArg: Int64, y yArg: Int64, completion: @escaping (Result<Int64, PigeonError>) -> Void)'));
     expect(code,
         contains('channel.sendMessage([xArg, yArg] as [Any?]) { response in'));
   });
@@ -1192,7 +1192,7 @@ void main() {
     expect(
         code,
         contains(
-            'func doit(foo fooArg: Int64?, completion: @escaping (Result<Void, FlutterError>) -> Void)'));
+            'func doit(foo fooArg: Int64?, completion: @escaping (Result<Void, PigeonError>) -> Void)'));
   });
 
   test('nonnull fields', () {
@@ -1572,6 +1572,6 @@ void main() {
     expect(
         code,
         contains(
-            'return FlutterError(code: "channel-error", message: "Unable to establish connection on channel: \'\\(channelName)\'.", details: "")'));
+            'return PigeonError(code: "channel-error", message: "Unable to establish connection on channel: \'\\(channelName)\'.", details: "")'));
   });
 }
diff --git a/packages/pigeon/tool/shared/generation.dart b/packages/pigeon/tool/shared/generation.dart
index 1cd3b6e5ea9..c4cf84582f1 100644
--- a/packages/pigeon/tool/shared/generation.dart
+++ b/packages/pigeon/tool/shared/generation.dart
@@ -89,6 +89,11 @@ Future<int> generateTestPigeons({required String baseDir}) async {
         ? 'FlutterError'
         : '${pascalCaseName}Error';
 
+    final bool swiftErrorUseDefaultErrorName = input == 'core_tests';
+
+    final String? swiftErrorClassName =
+        swiftErrorUseDefaultErrorName ? null : '${pascalCaseName}Error';
+
     // Generate the default language test plugin output.
     int generateCode = await runPigeon(
       input: './pigeons/$input.dart',
@@ -104,6 +109,7 @@ Future<int> generateTestPigeons({required String baseDir}) async {
       swiftOut: skipLanguages.contains(GeneratorLanguage.swift)
           ? null
           : '$outputBase/ios/Classes/$pascalCaseName.gen.swift',
+      swiftErrorClassName: swiftErrorClassName,
       // Windows
       cppHeaderOut: skipLanguages.contains(GeneratorLanguage.cpp)
           ? null
@@ -127,6 +133,7 @@ Future<int> generateTestPigeons({required String baseDir}) async {
       swiftOut: skipLanguages.contains(GeneratorLanguage.swift)
           ? null
           : '$outputBase/macos/Classes/$pascalCaseName.gen.swift',
+      swiftErrorClassName: swiftErrorClassName,
       suppressVersion: true,
       dartPackageName: 'pigeon_integration_tests',
     );
@@ -188,6 +195,7 @@ Future<int> runPigeon({
   String? kotlinErrorClassName,
   bool kotlinIncludeErrorClass = true,
   String? swiftOut,
+  String? swiftErrorClassName,
   String? cppHeaderOut,
   String? cppSourceOut,
   String? cppNamespace,
@@ -236,7 +244,9 @@ Future<int> runPigeon({
     objcSourceOut: objcSourceOut,
     objcOptions: ObjcOptions(prefix: objcPrefix),
     swiftOut: swiftOut,
-    swiftOptions: const SwiftOptions(),
+    swiftOptions: SwiftOptions(
+      errorClassName: swiftErrorClassName,
+    ),
     basePath: basePath,
     dartPackageName: dartPackageName,
   ));