I’ve been working on integrating Firebase Cloud Messaging (FCM) with my Flutter app, and I’ve run into an issue where the onMessageOpenedApp method is not triggered when I click on a notification while the app is in the background or terminated.

Here’s my setup:
Main Dart File (main.dart)

import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'my_app.dart';

@pragma('vm:entry-point')
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  await Firebase.initializeApp();
}

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

  runApp(MyApp());
}

Home Screen Dart File (home_screen.dart)

import 'package:flutter/material.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'firebase_messaging_service.dart';

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

class _HomeScreenState extends State<HomeScreen> {
  FirebaseMessagingService notificationServices = FirebaseMessagingService();

  @override
  void initState() {
    super.initState();
    notificationServices.requestNotificationPermission();
    notificationServices.foregroundMessage();
    notificationServices.firebaseInit(context);
    notificationServices.setupInteractMessage(context);
    notificationServices.isTokenRefresh();
    notificationServices.setupFirebase();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home Screen'),
      ),
      body: Center(
        child: Text('Flutter Firebase Messaging Demo'),
      ),
    );
  }
}

Firebase Messaging Service Class (firebase_messaging_service.dart)

import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'communication_view_model.dart';

class FirebaseMessagingService {
  FirebaseMessaging messaging = FirebaseMessaging.instance;
  final FlutterLocalNotificationsPlugin _flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();

  void isTokenRefresh() async {
    messaging.onTokenRefresh.listen((event) {
      debugPrint("Token refreshed: $event");
    });
  }

  Future<void> setupFirebase() async {
    messaging.getToken().then((value) {
      debugPrint("FCM Token: $value");
    });
  }

  void initLocalNotifications(BuildContext context, RemoteMessage message) async {
    var androidInitializationSettings = const AndroidInitializationSettings('@mipmap/ic_launcher');
    var iosInitializationSettings = const DarwinInitializationSettings();

    var initializationSettings = InitializationSettings(
      android: androidInitializationSettings,
      iOS: iosInitializationSettings,
    );

    await _flutterLocalNotificationsPlugin.initialize(
      initializationSettings,
      onDidReceiveNotificationResponse: (response) {
        handleMessage(context, message);
      },
    );
  }

  void firebaseInit(BuildContext context) {
    FirebaseMessaging.onMessage.listen((message) {
      RemoteNotification? notification = message.notification;
      AndroidNotification? android = message.notification?.android;

      if (kDebugMode) {
        print("Notification Title: ${notification?.title}");
        print("Notification Body: ${notification?.body}");
        print('Data: ${message.data}');
      }

      if (Platform.isIOS) {
        foregroundMessage();
      }

      if (Platform.isAndroid) {
        initLocalNotifications(context, message);
        showNotification(message);
      }
    });
  }

  void requestNotificationPermission() async {
    NotificationSettings settings = await messaging.requestPermission(
      alert: true,
      announcement: true,
      badge: true,
      carPlay: true,
      criticalAlert: true,
      provisional: true,
      sound: true,
    );

    if (settings.authorizationStatus == AuthorizationStatus.authorized) {
      if (kDebugMode) {
        print('User granted permission');
      }
    } else if (settings.authorizationStatus == AuthorizationStatus.provisional) {
      if (kDebugMode) {
        print('User granted provisional permission');
      }
    } else {
      if (kDebugMode) {
        print('User denied permission');
      }
    }
  }

  Future<void> showNotification(RemoteMessage message) async {
    AndroidNotificationChannel channel = AndroidNotificationChannel(
      'high_importance_channel',
      'High Importance Notifications',
      description: 'This channel is used for important notifications.',
      importance: Importance.max,
    );

    AndroidNotificationDetails androidNotificationDetails = AndroidNotificationDetails(
      channel.id,
      channel.name,
      channelDescription: channel.description,
      importance: Importance.high,
      priority: Priority.high,
      icon: '@mipmap/ic_launcher',
    );

    const DarwinNotificationDetails darwinNotificationDetails = DarwinNotificationDetails(
      presentAlert: true,
      presentBadge: true,
      presentSound: true,
    );

    NotificationDetails notificationDetails = NotificationDetails(
      android: androidNotificationDetails,
      iOS: darwinNotificationDetails,
    );

    Future.delayed(Duration.zero, () {
      _flutterLocalNotificationsPlugin.show(
        0,
        message.notification?.title,
        message.notification?.body,
        notificationDetails,
      );
    });
  }

  Future<void> setupInteractMessage(BuildContext context) async {
    FirebaseMessaging.instance.getInitialMessage().then((RemoteMessage? message) {
      if (message != null) {
        print("Initial message received: ${message.data}");
        handleMessage(context, message);
      }
    });

    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
      print("onMessageOpenedApp triggered with message: ${message.data}");
      handleMessage(context, message);
    });
  }

  void handleMessage(BuildContext context, RemoteMessage message) {
    // Handle the message
  }
}

Android Manifest (AndroidManifest.xml)

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.your.package">

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

    <application
        android:name="${applicationName}"
        android:label="your_app_name"
        android:icon="@mipmap/ic_launcher">
        
        <meta-data android:name="com.google.firebase.messaging.default_notification_icon"
            android:resource="@drawable/ic_launcher"/>
        <meta-data android:name="com.google.firebase.messaging.default_notification_color"
            android:resource="@color/green"/>
        <meta-data android:name="com.google.firebase.messaging.default_notification_channel_id"
            android:value="high_importance_channel"/>

        <activity
            android:name=".MainActivity"
            android:launchMode="singleTop">
            <intent-filter>
                <action android:name="FLUTTER_NOTIFICATION_CLICK"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </activity>

        <service
            android:name=".FirebaseService"
            android:exported="true">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT"/>
            </intent-filter>
        </service>
    </application>
</manifest>

Issue

I am receiving notifications when the app is in the background.
Clicking on the notification does not trigger the onMessageOpenedApp method.

What I’ve Tried

Verified that the notification payload includes click_action: "FLUTTER_NOTIFICATION_CLICK".
Added intent filter in AndroidManifest.xml for FLUTTER_NOTIFICATION_CLICK.
Initialized Firebase in main.dart and set up background message handler.
Used FlutterLocalNotificationsPlugin to show notifications.

Question

How can I ensure that onMessageOpenedApp is triggered when a notification is clicked while the app is in the background or terminated?

Any help would be greatly appreciated!