No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp() in Flutter and Firebase

Question

I am building a Flutter application and I have integrated Firebase, but I keep getting this error when I click on a button either to register, login or logout. I have seen other people have asked the same question, but none seems to work for me. I am using Flutter and Android Studio. How can I fix this problem?

This is an excerpt of my code

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.red,
      body: Center(
        child: Container(
          child: RaisedButton(
            onPressed: () {
              FirebaseAuth.instance.signOut().then((value) {
                Navigator.pushReplacement(
                    context,
                    MaterialPageRoute(
                        builder: (context) =>
                            LoginScreen()));
              });
            },
            child: Text("Logout"),
          )
        )
      )
    );
  }
}

Below is the thrown exception

══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

When the exception was thrown, this was the stack:

#0      MethodChannelFirebase.app (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:118:5)
#1      Firebase.app (package:firebase_core/src/firebase.dart:52:41)
#2      FirebaseAuth.instance (package:firebase_auth/src/firebase_auth.dart:37:47)
#3      _HomeScreenState.build.<anonymous closure> (package:cosytok/screens/home.dart:20:28)
#4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:992:19)
#5      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:1098:38)
#6      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:184:24)
#7      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:524:11)
#8      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:284:5)
#9      BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:219:7)
#10     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:477:9)
#11     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:78:12)
#12     PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:124:9)
#13     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
#14     PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:122:18)
#15     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:108:7)
#16     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:220:19)
#17     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
#18     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:158:7)
#19     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:104:7)
#20     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:88:7)
#24     _invoke1 (dart:ui/hooks.dart:267:10)
#25     _dispatchPointerDataPacket (dart:ui/hooks.dart:176:5)
(elided 3 frames from dart:async)

Handler: "onTap"
Recognizer:
  TapGestureRecognizer#f0104
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ Exception caught by gesture ═══════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

Answer 1

Starting Since August 17 2020

All Firebase versions have been updated and now you have to call Firebase.initializeApp() before using any Firebase product, for example:

First, all Firebase products now depend on firebase_core version (0.5.0+), therefore you need to add it in the pubspec.yaml file:

dependencies:
  flutter:
    sdk: flutter
  firebase_core : ^0.5.0
  # cloud_firestore: ^0.14.0 other firebase dependencies

Then you have to call Firebase.initializeApp():

First Example

import 'package:flutter/material.dart';

// Import the firebase_core plugin
import 'package:firebase_core/firebase_core.dart';

void main() {
  runApp(App());
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      // Initialize FlutterFire
      future: Firebase.initializeApp(),
      builder: (context, snapshot) {
        // Check for errors
        if (snapshot.hasError) {
          return SomethingWentWrong();
        }

        // Once complete, show your application
        if (snapshot.connectionState == ConnectionState.done) {
          return MyAwesomeApp();
        }

        // Otherwise, show something whilst waiting for initialization to complete
        return Loading();
      },
    );
  }
}

Second Example with Firestore:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: FirstRoute(title: 'First Route'),
    );
  }
}

class FirstRoute extends StatefulWidget {
  FirstRoute({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _FirstRouteState createState() => _FirstRouteState();
}

class _FirstRouteState extends State<FirstRoute> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("test"),
        ),
        body: FutureBuilder(
          future: getData(),
          builder: (context, AsyncSnapshot<DocumentSnapshot> snapshot) {
            if (snapshot.connectionState == ConnectionState.done) {
              return Column(
                children: [
                  Container(
                    height: 27,
                    child: Text(
                      "Name: ${snapshot.data.data()['name']}",
                      overflow: TextOverflow.fade,
                      style: TextStyle(fontSize: 20),
                    ),
                  ),
                ],
              );
            } else if (snapshot.connectionState == ConnectionState.none) {
              return Text("No data");
            }
            return CircularProgressIndicator();
          },
        ));
  }

  Future<DocumentSnapshot> getData() async {
    await Firebase.initializeApp();
    return await FirebaseFirestore.instance
        .collection("users")
        .doc("docID")
        .get();
  }
}

Third Example:

Initialize it in initState() then call setState() which will call the build() method.

  @override
  void initState() {
    super.initState();
    Firebase.initializeApp().whenComplete(() { 
      print("completed");
      setState(() {});
    });
  }

Fourth Example:

Initialize it in the main() method after calling WidgetsFlutterBinding.ensureInitialized();

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

Note: You only have to call initializeApp() once

Answer 2

1. Add to pubspec.yaml

   firebase_core :
   

2. add to main.dart

   import 'package:firebase_core/firebase_core.dart';
   
   void main() async {
      WidgetsFlutterBinding.ensureInitialized();
      await Firebase.initializeApp();
      runApp(MyApp());
   }
   

Answer 3

First, add this dependency:

firebase_core :

Second: in the project main function, add these two lines and make the function async:

void main() async {
    // These two lines
    WidgetsFlutterBinding.ensureInitialized();
    await Firebase.initializeApp();

    //
    runApp(MyApp());
}

Now you can use Firebase normally in any file or widget in the project.

The FutureBuilder widget will work either, but you must add it every time you want to access Firebase.

Answer 4

If you followed Peter's answer and are still getting the same error, check to make sure anything else you have in your main function comes after the await Firebase.initializeApp() call, like so:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  FirebaseCrashlytics.instance.setCrashlyticsCollectionEnabled(true);
  FlutterError.onError = FirebaseCrashlytics.instance.recordFlutterError;
  runApp(MyApp());
}

Answer 5

Peter's answer is perfect!! But if you still get an error in your code and following the Flutter Firebase codelab, note that those tutorials are outdated as of August 2020 and not updated yet.

You need to do many other changes like:

• replace .data with .data()
• replace updateData with update

Answer 6

You need to add await Firebase.initializeApp(); which is a Future. Do it inside the dart file that is running your Firebase function like below:

import 'package:firebase_core/firebase_core.dart';
...

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MaterialApp());
}

Answer 7

If you still have the problem when you leave the app to the main screen, you could add this to whatever .dart file using Firebase:

class App extends StatelessWidget {

  final Future<FirebaseApp> _initialization = Firebase.initializeApp();

  @override
  Widget build(BuildContext context) {

Or in the case of a StatefulWidget:

import 'package:flutter/material.dart';

// Import the firebase_core plugin
import 'package:firebase_core/firebase_core.dart';

void main() {
  runApp(App());
}

class App extends StatefulWidget {
  _AppState createState() => _AppState();
}

class _AppState extends State<App> {
  // Set default `_initialized` and `_error` state to false
  bool _initialized = false;
  bool _error = false;

  // Define an async function to initialize FlutterFire
  void initializeFlutterFire() async {
    try {
      // Wait for Firebase to initialize and set `_initialized` state to true
      await Firebase.initializeApp();
      setState(() {
        _initialized = true;
      });
    } catch(e) {
      // Set `_error` state to true if Firebase initialization fails
      setState(() {
        _error = true;
      });
    }
  }

  @override
  void initState() {
    initializeFlutterFire();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    // Show error message if initialization failed
    if(_error) {
      return SomethingWentWrong();
    }

    // Show a loader until FlutterFire is initialized
    if (!_initialized) {
      return Loading();
    }

    return MyAwesomeApp();
  }
}

For more information, check this link.

Answer 8

Flutter Web with Firebase

If you are using Flutter Web with Firebase make sure you have the SDKs installed in the body tag of your ./web/index.html

  <script src="https://www.gstatic.com/firebasejs/8.2.9/firebase-app.js"></script>
  <script src="https://www.gstatic.com/firebasejs/8.2.9/firebase-analytics.js"></script>

Furthermore, make sure you call firebase.initializeApp(...) with the configuration parameters in the index.html as well.

  <script>
    // Your web app's Firebase configuration
    // For Firebase JS SDK v7.20.0 and later, measurementId is optional
    var firebaseConfig = {
      apiKey: "AIz...",
      authDomain: "...",
      databaseURL: "https://<project-name>.firebaseio.com",
      projectId: "...",
      storageBucket: "<project-name>.appspot.com",
      messagingSenderId: "...",
      appId: "...",
      measurementId: "..."
    };
    firebase.initializeApp(firebaseConfig);
    firebase.analytics();
  </script>

At last configure firebase as described in Peter Haddad's answer:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

Answer 9

In my case it was because for the Web version you have to manually add stuff in the index.html file, not only the .js dependency, but the configuration. See Web Installation.

We tend to forget that for most stuff Flutter is compiled to the target without the need to change anything target-specific, but in this case one must add the configuration for each target.

Answer 10

Since August 2017, all Firebase services have been updated so that you have to call Firebase.initializeApp() in your main before you can use any of the Firebase products, for example:

If you want to use the firebase_core plugin in a flutter application, then in your pubspec.yaml file add the firebase_core as below

dependencies:
  flutter:
    sdk: flutter
  firebase_core : ^1.2.0

Then call the Firebase.initializeApp(): in your app. same as something below:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

Answer 11

You can initialize in the main.dart file as well like this using FutureBuilder.

 future: Firebase.initializeApp(),

Look at this example.

void main() {
  runApp(App());
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      // Initialize FlutterFire
      future: Firebase.initializeApp(),
      builder: (context, snapshot) {
       return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'NEWSAPI.org',
          home: SplashScreen(),
       
          routes: <String, WidgetBuilder>{
            SPLASH_SCREEN: (BuildContext context) => SplashScreen(),
          },);
      },
    );
  }
}

Answer 12

The problem for me was I initialized it without "await":

void main() async {
    WidgetsFlutterBinding.ensureInitialized();
    Firebase.initializeApp();

The correct way is:

void main() async {
    WidgetsFlutterBinding.ensureInitialized();
    await Firebase.initializeApp();