BlocProvider.of() called with a context that does not contain a Bloc of type Bloc<dynamic,dynamic>

Issue

Error: I/flutter ( 5919): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY
╞═══════════════════════════════════════════════════════════ I/flutter
( 5919): The following assertion was thrown building Builder:
I/flutter ( 5919): BlocProvider.of() called with a context
that does not contain a Bloc of type Bloc. I/flutter ( 5919): No ancestor could be found
starting from the context that was passed to I/flutter ( 5919):
BlocProvider.of>(). I/flutter ( 5919):
This can happen if the context you used comes from a widget above the
BlocProvider. I/flutter ( 5919): The context used was:
BlocBuilder, dynamic>(dirty, state: I/flutter (
5919): _BlocBuilderBaseState,
dynamic>#55a7d(lifecycle state: created)) I/flutter ( 5919): The
relevant error-causing widget was: I/flutter ( 5919): MaterialApp
/lib/main.dart:35:12

Here’s my main

void main() {
  final StorageRepository storageRepository = StorageRepository();
  final AuthenticationRepository authenticationRepository =
      AuthenticationRepository();
  runApp(BlocProvider<AuthenticationBloc>(
      create: (_) => AuthenticationBloc(
          authenticationRepository: authenticationRepository,
          storageRepository: storageRepository),
      child: MyApp()));
}

MaterialApp Widget

MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(primarySwatch: Colors.deepPurple),
      home: BlocBuilder(
        builder: (context, state) {
          print(state);
          if (state is Authenticated) {
            return MainPage();
          } else if (state is Unauthenticated) {
            return LoginPage();
          } else if (state is Uninitialized) {
            return SplashScreen();
          }

          return Container();
        },
      ),

Solution

You forget to give the Bloc and State type to the BlocBuilder Widget

MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(primarySwatch: Colors.deepPurple),
      /// You need to specify the type here, 
      /// that's why you got error Bloc<dynamic, dynamic>
      home: BlocBuilder<AuthenticationBloc, AuthenticationState>(
        builder: (context, state) {
          print(state);
          if (state is Authenticated) {
            return MainPage();
          } else if (state is Unauthenticated) {
            return LoginPage();
          } else if (state is Uninitialized) {
            return SplashScreen();
          }

          return Container();
        },
      ),

Answered By – Federick Jonathan

Answer Checked By – Katrina (FlutterFixes Volunteer)