Compilation errors in Sentry Flutter due to Kotlin API incompatibilities. (Language version 1.6 is no longer supported)

[juliansteenbakker]

Platform

Flutter Mobile Android

Obfuscation

Enabled

Debug Info

Enabled

Doctor

flutter doctor -v
[✓] Flutter (Channel stable, 3.32.5, on macOS 15.5 24F74 darwin-x64, locale nl-NL) [1.714ms]
• Flutter version 3.32.5 on channel stable at /usr/local/Caskroom/flutter/2.10.4/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision fcf2c11572 (7 days ago), 2025-06-24 11:44:07 -0700
• Engine revision dd93de6fb1
• Dart version 3.8.1
• DevTools version 2.45.1

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [3,9s]
• Android SDK at /Users/julian/Library/Android/sdk
• Platform android-35, build-tools 35.0.0
• Java binary at: /Users/julian/Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
This is the JDK bundled with the latest Android Studio installation on this machine.
To manually set the JDK path, use: flutter config --jdk-dir="path/to/jdk".
• Java version OpenJDK Runtime Environment (build 21.0.6+-13391695-b895.109)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.4) [4,1s]
• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 16F6
• CocoaPods version 1.16.2

[✓] Chrome - develop for the web [28ms]
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2025.1) [27ms]
• Android Studio at /Users/julian/Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 21.0.6+-13391695-b895.109)

[✓] VS Code (version 1.100.2) [25ms]
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension can be installed from:
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[✓] Connected device (3 available) [7,2s]
• SM X300 (mobile) • R52X50G5JMV • android-arm64 • Android 15 (API 35)
• macOS (desktop) • macos • darwin-x64 • macOS 15.5 24F74 darwin-x64
• Chrome (web) • chrome • web-javascript • Google Chrome 138.0.7204.92
! Error: Browsing on the local area network for iPad van Julian (2). Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)
! Error: Browsing on the local area network for iPhone. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)
! Error: Browsing on the local area network for iPhone. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)

[✓] Network resources [411ms]
• All expected network resources are available.

• No issues found!

Version

9.1.0

Steps to Reproduce

Build project with latest AGP, kotlin, gradle and compileSDK versions.

Expected Result

Build should run without issues

Actual Result

Task :sentry_flutter:compileDebugKotlin FAILED
e: Language version 1.6 is no longer supported; please, use version 1.8 or greater.

Same issue as #2455 but now with a new version.

sentry-dart/flutter/android/build.gradle

Line 58 in 92e3b9c

languageVersion = "1.6"

Are you willing to submit a PR?

Yes

[buenaflor]

Ah again..

I'll have a look, just wanna make sure that if we change this we don't break it for others but it's probably fine

[buenaflor]

Just double checked, the minimum req. Kotlin version for Flutter 3.24.0 (whcih is Sentry Flutter's min version) is 1.7.0. The Flutter templates though automatically use Kotlin 2.x.x

I think changing the languageVersion on our side to 1.8.0 would break it for some people but it's recommended by Flutter to upgrade anyway and that support for 1.7.0 will be dropped soon.

[buenaflor]

I sadly don't have stats on hand what Kotlin version is being used the most by our users

[juliansteenbakker]

Yeah these versions are quite hard to handle. I've tried 1.7, but i get the same message.

e: Language version 1.7 is no longer supported; please, use version 1.8 or greater.

I think the best would be to upgrade to 1.8, but add a note in the changelog and link people to a small guide on how to update their kotlin version to a more recent version.

[buenaflor]

Agreed 👍