android – Can’t show or schedule notification with flutter workmanager

I’m building an app with Flutter for Android and iOS that every day should check for new data and send a notification to the user. To achieve it, I’m using workmanager, to schedule the job, and flutter_local_notifications to show the notification.

When the job runs, no notification is shown and no exception get caught.

However, if I try to display a notification as per flutter_local_notifications docs, i.e. without workmanager, it works correctly.

This is a MRE of my main.dart that shows how I’m scheduling the job and showing the notification:

import 'dart:io';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:intl/intl.dart';
import 'package:timezone/data/latest_all.dart' as tz;
import 'package:timezone/timezone.dart' as tz;
import 'package:workmanager/workmanager.dart';
import 'package:intl/date_symbol_data_local.dart';


final localNotificationPlugin = FlutterLocalNotificationsPlugin();
bool _initialized = false;


void main() async {
  await initialize();
  Workmanager().initialize(callbackDispatcher);
  runApp(App());
}

@pragma('vm:entry-point')
Future initialize() async {
  WidgetsFlutterBinding.ensureInitialized();

  await initializeDateFormatting(Platform.localeName, null);
  await initLocalNotificationPlugin();

  tz.initializeTimeZones();
  tz.setLocalLocation(tz.getLocation(DateTime.now().timeZoneName));
}

Future initLocalNotificationPlugin() async {
  if (_initialized) {
    return;
  }

  _initialized = true;
  const AndroidInitializationSettings initializationSettingsAndroid = AndroidInitializationSettings('@mipmap/ic_launcher');
  final DarwinInitializationSettings initializationSettingsDarwin = DarwinInitializationSettings();
  final InitializationSettings initializationSettings = InitializationSettings(
      android: initializationSettingsAndroid,
      iOS: initializationSettingsDarwin
  );

  await localNotificationPlugin.initialize(initializationSettings);
}

@pragma('vm:entry-point')
void callbackDispatcher() {
  Workmanager().executeTask((task, inputData) async {
    print('callbackDispatcher');

    try {
      await initialize();
    } catch (e) {
      print("Exception on callbackDispatcher");
      print(e);
    }

    switch (task) {
      case "fetchAndShow":
        await sendNotification();
        break;
      default:
        // Handle unknown task types
        break;
    }

    return Future.value(true);
  });
}

@pragma('vm:entry-point')
Future sendNotification() async {
  try {
    await localNotificationPlugin.show(
      0,
      "Notification Title",
      "Notification Body",
      NotificationDetails(
        android: AndroidNotificationDetails("channel_id", "channel_name")
      )
    );
  } catch (e) {
    print('Exception on sendNotification');
    print(e);
  }
}

class App extends StatelessWidget {
@override
  Widget build(BuildContext context) {
    Workmanager().registerPeriodicTask('dataSync', 'fetchAndShow', frequency: Duration(days: 1));
    // Build logic
  }
}

I’m using:

• flutter: ^3.9.2
• intl: ^0.20.2
• flutter_local_notifications: ^19.5.0
• timezone: ^0.10.1
• workmanager: ^0.9.0+3