[Bug]: No implementation found for method finish on channel com.transistorsoft/flutter_background_fetch/methods

[galacticgibbon]

Required Reading

• Confirmed

Plugin Version

^1.5.0

Flutter Doctor

[✓] Flutter (Channel stable, 3.38.5, on macOS 15.5 24F74 darwin-arm64, locale en-GB)
[!] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    ! Some Android licenses not accepted. To resolve this, run: flutter doctor --android-licenses
[✓] Xcode - develop for iOS and macOS (Xcode 16.4)
[✓] Chrome - develop for the web
[✓] Connected device (4 available)
    ! Error: Browsing on the local area network for Development iPad. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
      The device must be opted into Developer Mode to connect wirelessly. (code -27)
    ! Error: Browsing on the local area network for Apple Watch. Ensure the device is unlocked and discoverable via Bluetooth. (code -27)
    ! Error: Browsing on the local area network for Dev phone. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
      The device must be opted into Developer Mode to connect wirelessly. (code -27)
[✓] Network resources

Mobile operating-system(s)

• iOS
• Android

Device Manufacturer(s) and Model(s)

SM-S921B 47% SM-X730 46%

Device operating-systems(s)

Android 16

What happened?

Not sure, this is happening in production and I can't reproduce.

Plugin Code and/or Config

/// Background Refresh Handler - Daily widget snapshot rebuild via background_fetch
///
/// ## Purpose
///
/// Ensures widget snapshots are regenerated daily so "today" queries reflect
/// the correct date. This is separate from FCM sync - FCM handles data freshness,
/// this handles date boundary changes.
///
/// ## Execution Context
///
/// background_fetch runs in the same process as the main app (similar to FCM).
/// Uses global database singletons to avoid lock conflicts.
///
/// ## When This Runs
///
/// - iOS: ~every 15 minutes (OS controlled, cannot be more frequent)
/// - Android: configurable minimum interval
/// - Only rebuilds if the day has changed since last refresh
library;

import 'dart:async';

import 'package:background_fetch/background_fetch.dart';
import 'package:bullet_common/common.dart';
import 'package:home_widget/home_widget.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

import 'init_services.dart';
import 'src/config/bullet_env.dart';
import 'src/features/widget/widget_snapshot_coordinator.dart';

/// Initialize background fetch - call before runApp()
Future<void> initBackgroundRefresh() async {
  if (!kIsMobile) return;

  try {
    await BackgroundFetch.configure(
      BackgroundFetchConfig(
        minimumFetchInterval: 15, // iOS minimum, Android can be lower
        stopOnTerminate: false,
        enableHeadless: true,
        startOnBoot: true,
        requiresBatteryNotLow: false,
        requiresCharging: false,
        requiresStorageNotLow: false,
        requiresDeviceIdle: false,
        requiredNetworkType: NetworkType.NONE,
      ),
      _onBackgroundFetch,
      _onBackgroundFetchTimeout,
    );

    // Register Android headless task for background fetch after app termination
    BackgroundFetch.registerHeadlessTask(_headlessTask);
  } catch (e, stackTrace) {
    // Background fetch initialization can fail on beta OS versions or
    // devices that don't support it - log and continue since it's optional
    await ErrorMonitor.captureException(
      e,
      stackTrace,
      handler: 'background_refresh_init',
      level: SentryLevel.warning,
    );
  }
}

/// Headless task for Android - runs even after app termination
@pragma('vm:entry-point')
void _headlessTask(HeadlessTask task) async {
  final taskId = task.taskId;

  if (task.timeout) {
    BackgroundFetch.finish(taskId);
    return;
  }

  await _handleBackgroundRefresh(taskId);
}

/// Event callback - called when background fetch fires
Future<void> _onBackgroundFetch(String taskId) async {
  await _handleBackgroundRefresh(taskId);
}

/// Timeout callback - must finish immediately
Future<void> _onBackgroundFetchTimeout(String taskId) async {
  BackgroundFetch.finish(taskId);
}

/// Core refresh logic - shared by foreground and headless handlers
Future<void> _handleBackgroundRefresh(String taskId) async {
  try {
    // Check if day changed since last refresh
    final lastRefreshDate = await HomeWidget.getWidgetData<String>(
      'last_refresh_date',
    );
    final today = Date.today().toString();

    if (lastRefreshDate == today) {
      // Already refreshed today, skip
      BackgroundFetch.finish(taskId);
      return;
    }

    final env = BulletEnv();

    // Create container with background-safe PowerSync override
    final container = ProviderContainer(
      overrides: [
        envProvider.overrideWithValue(env),
        powersyncInitializerProvider.overrideWith((ref) async {
          final authRepo = ref.watch(authRepositoryProvider);
          final packageInfo = ref
              .watch(packageInfoInitializerProvider)
              .requireValue;
          final connection = PowersyncConnection.instance;
          await connection.initBackground(
            app: env.app,
            authRepo: authRepo,
            packageInfo: packageInfo,
          );
          return connection;
        }),
      ],
    );

    try {
      await initServices(container: container);

      final coordinator = await container.read(
        widgetSnapshotCoordinatorProvider.future,
      );

      await coordinator.rebuildAllSnapshots(shouldNotify: true);

      // Mark today as refreshed
      await HomeWidget.saveWidgetData('last_refresh_date', today);
    } finally {
      container.dispose();
    }
  } catch (e, stackTrace) {
    await ErrorMonitor.captureException(
      e,
      stackTrace,
      handler: 'background_widget_refresh',
      level: SentryLevel.warning,
    );
  }

  BackgroundFetch.finish(taskId);
}

Relevant log output

Crashed in non-app: platform_channel.dart in MethodChannel._invokeMethod within flutter

Show 1 more frame
background_fetch.dart in BackgroundFetch.finish at line 582 within background_fetch
In App
No additional details are available for this frame.

[galacticgibbon]

Other related issues:
#348
#405
#353