MissingPluginException(No implementation found for method Firebase#initializeCore on channel plugins.flutter.io/firebase_core) on Android

Question

I am getting the above error when calling Firebase.initializeApp() in my flutter code. I have followed the documentation here: https://firebase.flutter.dev/docs

Here is my pubspec.yaml

dependencies:
  flutter:
    sdk: flutter
  firebase_core: ^0.5.0
  cloud_firestore: ^0.14.0
  firebase_auth: ^0.18.0
  fl_chart: ^0.11.0
  snapping_sheet: ^2.0.0
  flutter_svg: ^0.18.0
  flutter_redux: ^0.6.0
  strings: ^0.1.2
  random_string: ^2.1.0
  redux_thunk: ^0.3.0
  #  firebase_crashlytics: ^0.1.4+1
  dotted_line: ^2.0.1

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.3

dev_dependencies:
  flutter_test:
    sdk: flutter

Here is my flutter code:

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  SystemChrome.setEnabledSystemUIOverlays(SystemUiOverlay.values);

  final store = Store<AppState>(AppState.reducer, initialState: AppState.initial(), middleware: [thunkMiddleware]);

  runApp(
    FutureBuilder(
      future: Firebase.initializeApp(),
      builder: (context, snapshot) {
        // Check for errors
        if (snapshot.hasError) {
          log(snapshot.error.toString());
          return Container(color: Colors.red);
        }

        // Once complete, show your application
        if (snapshot.connectionState == ConnectionState.done) {
          return StoreProvider<AppState>(
            store: store,
            child: MoollaApp(store: store),
          );
        }

        // Otherwise, show something whilst waiting for initialization to complete
        return Container(color: Colors.green);
      },
    ),
  );
}

Here are the relevant part of my .gradle (app) file:

plugins {
    id "com.android.application"
    id "com.google.gms.google-services"
    id "kotlin-android"
    id "kotlin-android-extensions"
}

Here is my project gradle file:

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    ext.kotlin_version = "1.3.72"
    repositories {
        google()
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.2.0-alpha07'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.3'
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        mavenCentral()
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

and my Application class extension:

class MyApp : FlutterApplication() {
    override fun onCreate() {
        super.onCreate()
    }
}

As far as I can tell I have done everything correctly according to the docs.

Answer 1

Setting minifyEnabled & shrinkResources to false fixes it but why? I do not know. If somebody know please write a comment.

buildTypes {       
    release {
        signingConfig signingConfigs.release
        minifyEnabled false
        shrinkResources false
    }
}

Answer 2

Recently Added Firebase

Many Firebase packages include native code. In general any package with native code requires a complete reset of the app on the device; meaning deleting initial values and executing native code for the first time:

1. Uninstall the app from the device
2. Close and reopen Android Studio (sometimes optional)
3. Run/Start the application again

Done!

Answer 3

It's difficult to say exactly what's wrong without sifting through your entire project, but here are a few actions that will likely remedy the problem.

1. Run flutter doctor and verify everything is working as expected.
2. Run flutter clean followed by flutter pub get.

If you're still receiving the same error, then you likely made a mistake while editing one of the config files.

1. Compare your android/app/main/AndroidManifest.xml to the previous working version (specifically ensure you didn't accidentally delete any <meta-data /> tags as doing so would result in said error.
2. Do the same with the android/build.gradle and android/app/build.gradle.

Answer 4

What I ended up realizing after running into this issue, is that the error is super vague and doesn't necessarily mean there's a problem with firebase_core, rather there could be an issue with any of the Firebase plugins. So to narrow down where the issue was, I went through each firebase import individually and commented it out in the Pubspec.yaml file and ran it (along with commenting out all the code in my project that used that import), until I found which package was causing the issue.

For me, I was experiencing the issue only when running on iOS. It turned out that the firebase_messaging was the culprit and it was code that I had added to the iOS AppDelegate to handle the messaging that was no longer needed with the latest version of the firebase_messaging plugin.

Answer 5

I started a fresh project and made sure to change: classpath 'com.android.tools.build:gradle:4.2.0-alpha07' to the version officially supported: 3.5.0 Not sure if that downgrade was necessary because as I say, I restarted an entirely fresh project and something else may have effected it.

I also filed a ticket with Google which may prove helpful for anyone else in the future: https://github.com/FirebaseExtended/flutterfire/issues/3212#issuecomment-675407420