Blank Screen on running Flutter authentication

Question

I was trying to get authorization to work on my flutter app using Firebase but I don't know why I am getting a blank white screen on running my app.

The message attached below was the console output, but no specific red coloured urgent error message was printed out.

How do I resolve this issue?

main.dart

import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import 'widgets/authentication_service.dart';
import 'primary_page.dart';
import 'signin_page.dart';

Future<void> main() async{

  await Firebase.initializeApp();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MultiProvider(
      providers: [
        Provider<AuthenticationService>(
          create: (_) => AuthenticationService(FirebaseAuth.instance),
        ),
        StreamProvider(
          create: (context) => context.read<AuthenticationService>().authStateChanges,
        )
      ],
      child: MaterialApp(
        debugShowCheckedModeBanner: false,
        title: 'Flutter Auth',
        theme: ThemeData(
            primaryColor: Colors.pink,
            scaffoldBackgroundColor: Colors.black,
            textTheme: ThemeData.light().textTheme.copyWith(
                body1: TextStyle(
                  color: Color.fromRGBO(0, 0, 0, 1),
                ),
                body2: TextStyle(
                  color: Color.fromRGBO(0, 0, 0, 1),
                  fontWeight: FontWeight.bold,
                )

            )
        ),
        //home: LoginPage(),
        home: AuthenticationWrapper(),
      ),
    );
  }
}

class AuthenticationWrapper extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final firebaseUser = context.watch<User>();

    if (firebaseUser != null) {
      return PrimaryPage();
    }
    return SignInPage();
  }
}

I am sure that SignInPage() and PrimaryPage() are working correctly. Note: I've also tried to use an older version of package:provider which did not require initialData but that returns the same blank screen.

Output in console:

E/flutter (21352): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: ServicesBinding.defaultBinaryMessenger was accessed before the binding was initialized.
E/flutter (21352): If you're running an application and need to access the binary messenger before `runApp()` has been called (for example, during plugin initialization), then you need to explicitly call the `WidgetsFlutterBinding.ensureInitialized()` first.
E/flutter (21352): If you're running a test, you can call the `TestWidgetsFlutterBinding.ensureInitialized()` as the first line in your test's `main()` method to initialize the binding.
E/flutter (21352): #0      defaultBinaryMessenger.<anonymous closure> (package:flutter/src/services/binary_messenger.dart:97:7)
E/flutter (21352): #1      defaultBinaryMessenger (package:flutter/src/services/binary_messenger.dart:110:4)
E/flutter (21352): #2      MethodChannel.binaryMessenger (package:flutter/src/services/platform_channel.dart:142:62)
E/flutter (21352): #3      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:148:36)
E/flutter (21352): #4      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:331:12)
E/flutter (21352): #5      MethodChannel.invokeListMethod (package:flutter/src/services/platform_channel.dart:344:41)
E/flutter (21352): #6      MethodChannelFirebase._initializeCore (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:30:37)
E/flutter (21352): #7      MethodChannelFirebase.initializeApp (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:77:13)
E/flutter (21352): #8      Firebase.initializeApp (package:firebase_core/src/firebase.dart:41:47)
E/flutter (21352): #9      main (package:taskii/main.dart:11:18)
E/flutter (21352): #10     _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:140:25)
E/flutter (21352): #11     _rootRun (dart:async/zone.dart:1354:13)
E/flutter (21352): #12     _CustomZone.run (dart:async/zone.dart:1258:19)
E/flutter (21352): #13     _runZoned (dart:async/zone.dart:1788:10)
E/flutter (21352): #14     runZonedGuarded (dart:async/zone.dart:1776:12)
E/flutter (21352): #15     _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:133:5)
E/flutter (21352): #16     _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:283:19)
E/flutter (21352): #17     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)
E/flutter (21352): 

Solution

Add WidgetsFlutterBinding.ensureInitialized(); at first line of main function

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

You can take a look at library example https://pub.dev/packages/firebase_auth/example

Comments

[Very Useless]

Thanks, it works and I now understand why.

[chandru]

What is WidgetsFlutterBinding.ensureInitialized(); actually mean??