FirebaseAuth instance is null for Flutter Web

[vinceMuni]

I tried to deploy my app on Chrome.
Trying to sign in, it fails because FirebaseAuth.instance results as null.
Is there any adding configuration I need to setup?

PS: It runs smoothly on both iOS and Android

[iapicca]

Hi @vinceMuni
can you please provide your updated flutter doctor -v
and your flutter run --verbose?
Also, to better address the issue, would be helpful
if you could post a minimal code sample
or the steps to reproduce the problem.
Thank you

[vinceMuni]

Hi there, yes sure. Here following my flutter doctor:

[√] Flutter (Channel beta, v1.12.13+hotfix.6, on Microsoft Windows [Versione 10.0.18363.535], locale it-IT)
    • Flutter version 1.12.13+hotfix.6 at C:\vince\flutter
    • Framework revision 18cd7a3601 (8 days ago), 2019-12-11 06:35:39 -0800
    • Engine revision 2994f7e1e6
    • Dart version 2.7.0


[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at C:\Users\aleol\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files (x86)\Google\Chrome\Application\chrome.exe

[√] Android Studio (version 3.5)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 41.0.2
    • Dart plugin version 191.8593
    • Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)

[√] IntelliJ IDEA Community Edition (version 2019.1)
    • IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2019.1.2
    • Flutter plugin version 36.0.7
    • Dart plugin version 191.7830

[√] Connected device (2 available)
    • Chrome     • chrome     • web-javascript • Google Chrome 79.0.3945.88
    • Web Server • web-server • web-javascript • Flutter Tools

• No issues found!

Here my flutter run --verbose:

[  +31 ms] executing: [C:\vince\flutter\] git -c log.showSignature=false log -n 1 --pretty=format:%H
[  +87 ms] Exit code 0 from: git -c log.showSignature=false log -n 1 --pretty=format:%H
[   +1 ms] 18cd7a3601bcffb36fdf2f679f763b5e827c2e8e
[   +1 ms] executing: [C:\vince\flutter\] git describe --match v*.*.* --first-parent --long --tags
[ +127 ms] Exit code 0 from: git describe --match v*.*.* --first-parent --long --tags
[   +4 ms] v1.12.13+hotfix.6-0-g18cd7a360
[  +17 ms] executing: [C:\vince\flutter\] git rev-parse --abbrev-ref --symbolic @{u}
[  +82 ms] Exit code 0 from: git rev-parse --abbrev-ref --symbolic @{u}
[   +1 ms] origin/beta
[   +1 ms] executing: [C:\vince\flutter\] git ls-remote --get-url origin
[  +70 ms] Exit code 0 from: git ls-remote --get-url origin
[   +1 ms] https://github.com/flutter/flutter.git
[ +145 ms] executing: [C:\vince\flutter\] git rev-parse --abbrev-ref HEAD
[  +72 ms] Exit code 0 from: git rev-parse --abbrev-ref HEAD
[   +1 ms] beta
[ +155 ms] executing: C:\Users\aleol\AppData\Local\Android\sdk\platform-tools\adb.exe devices -l
[  +51 ms] Exit code 0 from: C:\Users\aleol\AppData\Local\Android\sdk\platform-tools\adb.exe devices -l
[   +1 ms] List of devices attached
[  +33 ms] Artifact Instance of 'AndroidMavenArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'AndroidInternalBuildArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'IOSEngineArtifacts' is not required, skipping update.
[  +10 ms] Artifact Instance of 'WindowsEngineArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'MacOSEngineArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'LinuxEngineArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not required, skipping update.
[   +1 ms] Artifact Instance of 'FlutterRunnerDebugSymbols' is not required, skipping update.
[  +81 ms] Found plugin cloud_firestore at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\cloud_firestore-0.12.9+4\
[  +12 ms] Found plugin cloud_functions at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\cloud_functions-0.4.1+5\
[  +24 ms] Found plugin firebase_auth at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.15.2\
[   +6 ms] Found plugin firebase_auth_web at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth_web-0.1.1+1\
[   +3 ms] Found plugin firebase_core at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_core-0.4.0+9\
[  +25 ms] Found plugin flutter_webview_plugin at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_webview_plugin-0.3.8\
[   +3 ms] Found plugin geocoder at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\geocoder-0.2.1\
[   +2 ms] Found plugin geoflutterfire at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\geoflutterfire-2.0.3+5\
[   +7 ms] Found plugin image_picker at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\image_picker-0.6.1+4\
[   +7 ms] Found plugin path_provider at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\path_provider-1.4.2\
[   +9 ms] Found plugin share at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\share-0.6.2+1\
[  +17 ms] Found plugin url_launcher at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\url_launcher-5.1.4\
[  +46 ms] Found plugin cloud_firestore at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\cloud_firestore-0.12.9+4\
[   +2 ms] Found plugin cloud_functions at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\cloud_functions-0.4.1+5\
[   +8 ms] Found plugin firebase_auth at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.15.2\
[   +4 ms] Found plugin firebase_auth_web at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth_web-0.1.1+1\
[   +1 ms] Found plugin firebase_core at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_core-0.4.0+9\
[  +13 ms] Found plugin flutter_webview_plugin at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_webview_plugin-0.3.8\
[   +2 ms] Found plugin geocoder at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\geocoder-0.2.1\
[   +2 ms] Found plugin geoflutterfire at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\geoflutterfire-2.0.3+5\
[   +4 ms] Found plugin image_picker at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\image_picker-0.6.1+4\
[   +6 ms] Found plugin path_provider at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\path_provider-1.4.2\
[   +6 ms] Found plugin share at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\share-0.6.2+1\
[   +8 ms] Found plugin url_launcher at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\url_launcher-5.1.4\
[  +57 ms] Generating C:\vince\boardee_host\boardee_host\android\app\src\main\java\io\flutter\plugins\GeneratedPluginRegistrant.java
[ +147 ms] Launching lib\main.dart on Chrome in debug mode...
[   +2 ms] Building application for the web...
[ +320 ms] Found plugin cloud_firestore at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\cloud_firestore-0.12.9+4\
[   +2 ms] Found plugin cloud_functions at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\cloud_functions-0.4.1+5\
[   +5 ms] Found plugin firebase_auth at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.15.2\
[   +1 ms] Found plugin firebase_auth_web at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth_web-0.1.1+1\
[   +1 ms] Found plugin firebase_core at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_core-0.4.0+9\
[   +7 ms] Found plugin flutter_webview_plugin at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_webview_plugin-0.3.8\
[   +2 ms] Found plugin geocoder at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\geocoder-0.2.1\
[   +1 ms] Found plugin geoflutterfire at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\geoflutterfire-2.0.3+5\
[   +3 ms] Found plugin image_picker at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\image_picker-0.6.1+4\
[   +3 ms] Found plugin path_provider at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\path_provider-1.4.2\
[   +5 ms] Found plugin share at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\share-0.6.2+1\
[   +7 ms] Found plugin url_launcher at C:\vince\flutter\.pub-cache\hosted\pub.dartlang.org\url_launcher-5.1.4\
[+13754 ms] Starting daemon...
[ +367 ms] Initializing inputs
[ +829 ms] Building new asset graph...
[+2879 ms] Building new asset graph completed, took 2.9s

[   +1 ms] Checking for unexpected pre-existing outputs....
[   +1 ms] Checking for unexpected pre-existing outputs. completed, took 1ms

[   +9 ms] Initializing inputs
[   +4 ms] Building new asset graph...
[        ] Building new asset graph completed, took 2.9s
[        ] Checking for unexpected pre-existing outputs....
[        ] Checking for unexpected pre-existing outputs. completed, took 1ms
[ +429 ms] Serving DevTools at http://127.0.0.1:50076

[+1526 ms] About to build [web]...
[  +13 ms] Running build...
[ +975 ms] 1.0s elapsed, 86/89 actions completed.
[+1003 ms] 2.0s elapsed, 187/191 actions completed.
[+1096 ms] 3.1s elapsed, 293/299 actions completed.
[ +136 ms] Unable to read module information for package:boardee_host, make sure you have a dependency on it in your pubspec.
[+1066 ms] 4.3s elapsed, 468/483 actions completed.
[+1002 ms] 5.3s elapsed, 608/617 actions completed.
[+1006 ms] 6.3s elapsed, 727/742 actions completed.
[+1093 ms] 7.4s elapsed, 822/838 actions completed.
[+1090 ms] 8.5s elapsed, 1051/1055 actions completed.
[+1087 ms] 9.6s elapsed, 1305/1312 actions completed.
[ +215 ms] Unable to read module information for package:googleapis_auth, make sure you have a dependency on it in your pubspec.
[ +206 ms] Unable to read module information for package:service_worker, make sure you have a dependency on it in your pubspec.
[+1087 ms] 11.1s elapsed, 1619/1635 actions completed.
[+1271 ms] 12.4s elapsed, 1779/1799 actions completed.
[+1019 ms] 13.4s elapsed, 1863/1865 actions completed.
[ +636 ms] Unable to read module information for package:googleapis_auth, make sure you have a dependency on it in your pubspec.
[   +2 ms] Unable to read module information for package:service_worker, make sure you have a dependency on it in your pubspec.
[+1059 ms] 15.1s elapsed, 1998/2001 actions completed.
[  +55 ms] Unable to read module information for package:googleapis_auth, make sure you have a dependency on it in your pubspec.
[   +2 ms] Unable to read module information for package:service_worker, make sure you have a dependency on it in your pubspec.
[+1086 ms] 16.2s elapsed, 2006/2141 actions completed.
[+1132 ms] 17.3s elapsed, 2006/2141 actions completed.
[+1112 ms] 18.5s elapsed, 2014/2149 actions completed.
[+1077 ms] 19.5s elapsed, 2026/2152 actions completed.
[ +954 ms] 20.5s elapsed, 2034/2156 actions completed.
[+1097 ms] 21.6s elapsed, 2044/2157 actions completed.
[+1129 ms] 22.7s elapsed, 2066/2159 actions completed.
[+1057 ms] 23.8s elapsed, 2079/2163 actions completed.
[+1012 ms] 24.8s elapsed, 2083/2166 actions completed.
[+1110 ms] 25.9s elapsed, 2086/2166 actions completed.
[+1012 ms] 26.9s elapsed, 2097/2174 actions completed.
[+1062 ms] 28.0s elapsed, 2105/2182 actions completed.
[+1004 ms] 29.0s elapsed, 2115/2189 actions completed.
[+1040 ms] 30.0s elapsed, 2118/2191 actions completed.
[+1036 ms] 31.0s elapsed, 2120/2191 actions completed.
[+1103 ms] 32.1s elapsed, 2137/2196 actions completed.
[ +970 ms] 33.1s elapsed, 2147/2197 actions completed.
[+1051 ms] 34.2s elapsed, 2153/2199 actions completed.
[+1001 ms] 35.2s elapsed, 2154/2200 actions completed.
[+1034 ms] 36.2s elapsed, 2167/2208 actions completed.
[+1120 ms] 37.3s elapsed, 2185/2214 actions completed.
[+1032 ms] 38.4s elapsed, 2213/2230 actions completed.
[+1108 ms] 39.5s elapsed, 2225/2242 actions completed.
[ +999 ms] 40.5s elapsed, 2242/2259 actions completed.
[+1100 ms] 41.6s elapsed, 2265/2274 actions completed.
[+1004 ms] 42.6s elapsed, 2271/2274 actions completed.
[ +982 ms] Running build completed, took 43.4s

[   +1 ms] Caching finalized dependency graph...
[   +8 ms] Caching finalized dependency graph completed, took 202ms

[   +8 ms] Succeeded after 43.6s with 2153 outputs (4021 actions)

[  +12 ms] Building application for the web... (completed in 63,8s)
[   +1 ms] Attempting to connect to browser instance..
[+15138 ms] Debug service listening on ws://127.0.0.1:50159/vD8_VW60TZU=

[ +753 ms] Attempting to connect to browser instance.. (completed in 15,9s)
[   +3 ms] Warning: Flutter's support for web development is not stable yet and hasn't
[   +1 ms] been thoroughly tested in production environments.
[        ] For more information see https://flutter.dev/web
[   +1 ms] �  To hot restart changes while running, press "r". To hot restart (and refresh the browser), press "R".
[   +2 ms] For a more detailed help message, press "h". To quit, press "q".
[  +11 ms] Debug service listening on ws://127.0.0.1:50159/vD8_VW60TZU=
[  +31 ms]       Failed to load asset at path: packages/build_web_compilers/src/dev_compiler/dart_sdk.js.

                 Status code: 404

                 Headers:
                 {
             "date": "Thu, 19 Dec 2019 15:40:35 GMT",
             "content-length": "9",
             "x-frame-options": "SAMEORIGIN",
             "content-type": "text/plain; charset=utf-8",
             "x-xss-protection": "1; mode=block",
             "x-content-type-options": "nosniff",
             "server": "dart:io with Shelf",
             "via": "1.1 shelf_proxy"
           }

                 Content:
                 Not Found}

[ +160 ms] Error while trying to load font family "Futura":
                    NetworkError: A network error occurred.
[+1815 ms] Connection ConnectionState.waiting
[  +77 ms] Connection ConnectionState.done
[ +433 ms] Error while trying to load an asset: Failed to load asset at "assets/assets/images/background/3x/sfondo.png" (404)
[ +622 ms] ══╡ EXCEPTION CAUGHT BY IMAGE RESOURCE SERVICE ╞════════════════════════════════════════════════════
[   +3 ms] The following assertion was thrown resolving an image codec:
[   +4 ms] Unable to load asset: assets/images/background/3x/sfondo.png
[   +1 ms] When the exception was thrown, this was the stack:
[   +1 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 196:49  throw_
[   +4 ms] package:flutter/src/services/asset_bundle.dart 221:55                                                                                                                   load
[   +2 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 47:50            onValue
[   +2 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1134:38
_rootRunUnary
[   +4 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1031:19
runUnary
[   +1 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 139:18
handleValue
[   +3 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 680:44
           handleValueCallback
[   +1 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 709:32
           _propagateToListeners
[   +9 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 524:5
           [_completeWithValue]
[   +2 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 554:7                                     <fn>
[   +2 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1126:13
_rootRun
[   +2 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1023:19                                          run
[   +3 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 925:7
runGuarded
[   +2 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 965:23
callback
[   +3 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/schedule_microtask.dart 43:11
_microtaskLoop
[   +3 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/schedule_microtask.dart 52:5
           _startMicrotaskLoop
[   +1 ms] package:build_web_compilers/src/dev_compiler/C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 168:15           <fn>
[   +2 ms] Image provider: AssetImage(bundle: null, name: "assets/images/background/3x/sfondo.png")
[   +1 ms] Image key: AssetBundleImageKey(bundle: PlatformAssetBundle#a854c(), name:
[   +1 ms] "assets/images/background/3x/sfondo.png", scale: 1)
[        ] ════════════════════════════════════════════════════════════════════════════════════════════════════

Here the code snippet where I am using FirebaseAuth:

 static Future<String> signIn(String email, String password) async {
    try {
        print('IS WEB!');
        FirebaseAuth _auth = FirebaseAuth.instance;
        print('AUTH WEB IS $_auth');
        AuthResult result = await _auth.signInWithEmailAndPassword(email: email, password: password);
        return result.user.uid;
    } catch (e) {
      print('Error auth: $e');
      return Future.error(e);
    }
  }

Thank you for your help.

[ditman]

Did you do the setup changes on web/index.html?

Take a look at the web example to see the initialization.

[TannerYoung]

This really needs to be added to the documentation at one of:

https://pub.dev/packages/firebase_auth
https://pub.dev/packages/firebase_auth_web

I hadn't seen anything about setting up the script tag before this.

[ditman]

@TannerYoung @vinceMuni you're right, I think it's a good action item for this ticket.

What documentation changes would you like to see? A specific "web setup" in the core plugin, and setup in the web version?

A link to the web example?

[TannerYoung]

I think specifically mentioning the data that needs to be added from the guide in step 1 of https://firebase.google.com/docs/web/setup#register-app

I already had my firebase app set up for android, and I just wasn't aware of the significance of adding web capabilities to the firebase app in the console

[ditman]

Related issue: #1746

[dimitris1pana]

What is missing from the firebase SDK web widget is this

<script src="https://www.gstatic.com/firebasejs/7.13.2/firebase-auth.js"></script>

As previously mentioned the snippet with the auth.js script should be added at the end of the body and before the script containing the dart.js

[ditman]

@dimitris1pana what do you mean by "the firebase SDK web widget"? Thanks!

[dimitris1pana]

https://firebase.google.com/docs/web/setup

[ditman]

https://firebase.google.com/docs/web/setup

@dimitris1pana but Step 3 of that page, in the "From CDN" setup, lists firebase-auth.js, doesn't it?

From the link you shared:

<body>
  <!-- Insert these scripts at the bottom of the HTML, but before you use any Firebase services -->

  <!-- Firebase App (the core Firebase SDK) is always required and must be listed first -->
  <script src="https://www.gstatic.com/firebasejs/7.13.2/firebase-app.js"></script>

  <!-- If you enabled Analytics in your project, add the Firebase SDK for Analytics -->
  <script src="https://www.gstatic.com/firebasejs/7.13.2/firebase-analytics.js"></script>

  <!-- Add Firebase products that you want to use -->
  <script src="https://www.gstatic.com/firebasejs/7.13.2/firebase-auth.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.13.2/firebase-firestore.js"></script>
</body>