W/FLTFireMsgService( 8777): Flutter- FCM A background message could not be handled in Dart

user_15235664 0
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I've updated firebase messaging to the latest version and implement the new modifications but with firebase_messaging: ^8.0.0 and above I am not able to navigate to the respective screens when I push the notification icon if the application running in the background.

this is the code

class PushNotificationService
{
  final FirebaseMessaging messaging  = FirebaseMessaging.instance;

  Future initialize(context) async{
    
    FirebaseMessaging.instance.getInitialMessage().then((RemoteMessage message)  => (Map<String, dynamic> message) async{
      retrieveRideRequestInfo(getRideRequestId(message), context);
    });

    FirebaseMessaging.onMessage.listen((RemoteMessage message)  => (Map<String, dynamic> message) async {

          retrieveRideRequestInfo(getRideRequestId(message), context);
    });

    
    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message)  => (Map<String, dynamic> message) async{

          retrieveRideRequestInfo(getRideRequestId(message), context);
    });
  }

  Future<String> getToken() async{
    String token = await messaging.getToken();
    //String token = await firebaseMessaging.getToken();
    print("This is token :: ");
    print(token);
    driversRef.child(currentfirebaseUser.uid).child("token").set(token);
    messaging .subscribeToTopic("alldrivers");
    messaging .subscribeToTopic("allusers");

  }
  String getRideRequestId(Map<String, dynamic> message){
    String rideRequestId = "";

    if(Platform.isAndroid)
    {

      rideRequestId = message['data']['ride_request_id'];
    }
    else{

      rideRequestId = message['ride_request_id'];


    }

    return rideRequestId;
  }
    void retrieveRideRequestInfo(String rideRequestId, BuildContext context){

    newRequestsRef.child(rideRequestId).once().then((DataSnapshot dataSnapshot)
    {
      if (dataSnapshot.value != null) {



        double pickUpLocationLat = double.parse(
            dataSnapshot.value['pickup']['latitude'].toString());
        double pickUpLocationLng = double.parse(
            dataSnapshot.value['pickup']['longitude'].toString());
        String pickUpAddress = dataSnapshot.value['pickup_address'].toString();
        }
    });


    }


}

Run log:

D/FLTFireMsgReceiver( 8777): broadcast received for message

W/FLTFireMsgService( 8777): A background message could not be handled in Dart as no onBackgroundMessage handler has been registered.

W/FirebaseMessaging( 8777): Unable to log event: analytics library is missing W/FirebaseMessaging( 8777): Notification Channel set in AndroidManifest.xml has not been created by the app. Default value will be used. E/NotificationManager( 8777): notifyAsUser: tag=FCM-Notification:111236427, id=0, user=UserHandle{0}

dart flutter android
2 Answers

Handling messages whilst your application is in the background is a little different. Messages can be handled via the onBackgroundMessage handler. When received, an isolate is spawned (Android only, iOS/macOS does not require a separate isolate) allowing you to handle messages even when your application is not running.

There are a few things to keep in mind about your background message handler:

It must not be an anonymous function. It must be a top-level function (e.g. not a class method which requires initialization).

Example:

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  // If you're going to use other Firebase services in the background, such as Firestore,
  // make sure you call `initializeApp` before using other Firebase services.
  await Firebase.initializeApp();

  print("Handling a background message: ${message.messageId}");
}

void main() {
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
  runApp(MyApp());
}

Please go to official flutterfire docs for more information:

https://firebase.flutter.dev/docs/messaging/usage/

user_145720760

Had the same issue, with not working background Data FCM notifications. After investigation, I upgraded local notifications to the latest available and that fixed the problem!

dependencies:
  flutter_local_notifications: ^9.7.0
user_66295150
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