diff --git a/mobile/lib/models/backup/backup_state.model.dart b/mobile/lib/models/backup/backup_state.model.dart
index f5d667ce66..1671297b88 100644
--- a/mobile/lib/models/backup/backup_state.model.dart
+++ b/mobile/lib/models/backup/backup_state.model.dart
@@ -22,7 +22,7 @@ class BackUpState {
   final DateTime progressInFileSpeedUpdateTime;
   final int progressInFileSpeedUpdateSentBytes;
   final double iCloudDownloadProgress;
-  final Completer cancelToken;
+  final Completer<void> cancelToken;
   final ServerDiskInfo serverInfo;
   final bool autoBackup;
   final bool backgroundBackup;
diff --git a/mobile/lib/providers/backup/drift_backup.provider.dart b/mobile/lib/providers/backup/drift_backup.provider.dart
index 93eaa42ab7..ae5823b0f6 100644
--- a/mobile/lib/providers/backup/drift_backup.provider.dart
+++ b/mobile/lib/providers/backup/drift_backup.provider.dart
@@ -108,7 +108,7 @@ class DriftBackupState {
   final BackupError error;
 
   final Map<String, DriftUploadStatus> uploadItems;
-  final Completer? cancelToken;
+  final Completer<void>? cancelToken;
 
   final Map<String, double> iCloudDownloadProgress;
 
@@ -132,7 +132,7 @@ class DriftBackupState {
     bool? isSyncing,
     BackupError? error,
     Map<String, DriftUploadStatus>? uploadItems,
-    Completer? cancelToken,
+    Completer<void>? cancelToken,
     Map<String, double>? iCloudDownloadProgress,
   }) {
     return DriftBackupState(
diff --git a/mobile/lib/services/background.service.dart b/mobile/lib/services/background.service.dart
index 4451614eda..0f2961c151 100644
--- a/mobile/lib/services/background.service.dart
+++ b/mobile/lib/services/background.service.dart
@@ -41,7 +41,7 @@ class BackgroundService {
   static const MethodChannel _backgroundChannel = MethodChannel('immich/backgroundChannel');
   static const notifyInterval = Duration(milliseconds: 400);
   bool _isBackgroundInitialized = false;
-  Completer? _cancellationToken;
+  Completer<void>? _cancellationToken;
   bool _canceledBySystem = false;
   int _wantsLockTime = 0;
   bool _hasLock = false;
@@ -464,7 +464,7 @@ class BackgroundService {
     return ok;
   }
 
-  void _onAssetUploaded({bool shouldNotify = false}) async {
+  void _onAssetUploaded({bool shouldNotify = false}) {
     if (!shouldNotify) {
       return;
     }
diff --git a/mobile/lib/services/backup.service.dart b/mobile/lib/services/backup.service.dart
index 5b8b5540ca..7a19155576 100644
--- a/mobile/lib/services/backup.service.dart
+++ b/mobile/lib/services/backup.service.dart
@@ -234,7 +234,7 @@ class BackupService {
 
   Future<bool> backupAsset(
     Iterable<BackupCandidate> assets,
-    Completer cancelToken, {
+    Completer<void> cancelToken, {
     bool isBackground = false,
     PMProgressHandler? pmProgressHandler,
     required void Function(SuccessUploadAsset result) onSuccess,
diff --git a/mobile/lib/services/foreground_upload.service.dart b/mobile/lib/services/foreground_upload.service.dart
index 95bd88e094..ce02c9c56b 100644
--- a/mobile/lib/services/foreground_upload.service.dart
+++ b/mobile/lib/services/foreground_upload.service.dart
@@ -153,7 +153,7 @@ class ForegroundUploadService {
   /// Upload files from shared intent
   Future<void> uploadShareIntent(
     List<File> files, {
-    Completer? cancelToken,
+    Completer<void>? cancelToken,
     void Function(String fileId, int bytes, int totalBytes)? onProgress,
     void Function(String fileId)? onSuccess,
     void Function(String fileId, String errorMessage)? onError,