files-community · woojh3690 · Jun 19, 2026
diff --git a/src/Files.App/Data/Items/ListedItem.cs b/src/Files.App/Data/Items/ListedItem.cs
@@ -117,9 +117,8 @@ public string[] FileTags
 					// only set the tags if the file tags have been changed
 					if (fileTagsInitialized)
 					{
-						var dbInstance = FileTagsHelper.GetDbInstance();
-						dbInstance.SetTags(ItemPath, FileFRN, value);
-						FileTagsHelper.WriteFileTag(ItemPath, value);
+						// Update the registry index and ADS as one synchronized operation.
+						_ = FileTagsHelper.SetTagsAndWriteFileTagAsync(ItemPath, FileFRN, value);
 					}
 
 					HasTags = !FileTags.IsEmpty();

diff --git a/src/Files.App/Helpers/Application/AppLifecycleHelper.cs b/src/Files.App/Helpers/Application/AppLifecycleHelper.cs
@@ -111,23 +111,33 @@ await Task.WhenAll(
 			// Start non-critical tasks without waiting for them to complete
 			_ = Task.Run(async () =>
 			{
-				await Task.WhenAll(
-					OptionalTaskAsync(CloudDrivesManager.UpdateDrivesAsync(), generalSettingsService.ShowCloudDrivesSection),
-					App.LibraryManager.UpdateLibrariesAsync(),
-					OptionalTaskAsync(WSLDistroManager.UpdateDrivesAsync(), generalSettingsService.ShowWslSection),
-					OptionalTaskAsync(App.FileTagsManager.UpdateFileTagsAsync(), generalSettingsService.ShowFileTagsSection),
-					jumpListService.InitializeAsync()
-				);
-
-				//Start the tasks separately to reduce resource contention
-				await Task.WhenAll(
-					addItemService.InitializeAsync(),
-					ContextMenu.WarmUpQueryContextMenuAsync()
-				);
+				try
+				{
+					await Task.WhenAll(
+						OptionalTaskAsync(CloudDrivesManager.UpdateDrivesAsync(), generalSettingsService.ShowCloudDrivesSection),
+						App.LibraryManager.UpdateLibrariesAsync(),
+						OptionalTaskAsync(WSLDistroManager.UpdateDrivesAsync(), generalSettingsService.ShowWslSection),
+						OptionalTaskAsync(App.FileTagsManager.UpdateFileTagsAsync(), generalSettingsService.ShowFileTagsSection),
+						jumpListService.InitializeAsync()
+					);
+
+					// Run these tasks after the preceding initialization to reduce resource contention.
+					await Task.WhenAll(
+						addItemService.InitializeAsync(),
+						ContextMenu.WarmUpQueryContextMenuAsync()
+					);
+				}
+				catch (Exception ex)
+				{
+					App.Logger.LogWarning(ex, "Failed to initialize non-critical app services.");
+				}
+				finally
+				{
+					// Run the tag database scan even if a preceding background task fails.
+					SafetyExtensions.IgnoreExceptions(FileTagsHelper.UpdateTagsDb, App.Logger);
+				}
 			});
 
-			FileTagsHelper.UpdateTagsDb();
-
 			_ = Task.Run(async () =>
 			{
 				// The follwing method invokes UI thread, so we run it in a separate task

diff --git a/src/Files.App/MainWindow.xaml.cs b/src/Files.App/MainWindow.xaml.cs
@@ -337,9 +337,8 @@ x.tabItem.NavigationParameter.NavigationParameter is PaneNavigationArguments pan
 							if (fileFRN is not null)
 							{
 								var tagUid = tag is not null ? new[] { tag.Uid } : [];
-								var dbInstance = FileTagsHelper.GetDbInstance();
-								dbInstance.SetTags(file, fileFRN, tagUid);
-								FileTagsHelper.WriteFileTag(file, tagUid);
+								// Update the registry index and ADS as one synchronized operation.
+								_ = FileTagsHelper.SetTagsAndWriteFileTagAsync(file, fileFRN, tagUid);
 							}
 						}
 						break;

diff --git a/src/Files.App/Utils/FileTags/FileTagsDatabase.cs b/src/Files.App/Utils/FileTags/FileTagsDatabase.cs
@@ -14,9 +14,30 @@ namespace Files.App.Utils.FileTags
 	public sealed class FileTagsDatabase
 	{
 		private static string? _FileTagsKey;
+
+		// Protect the registry path and FRN indices from concurrent updates.
+		internal static object SyncRoot { get; } = new();
+
 		private string? FileTagsKey => _FileTagsKey ??= SafetyExtensions.IgnoreExceptions(() => @$"Software\Files Community\{Package.Current.Id.Name}\v1\FileTags");
 
+		internal static void RunSynchronized(Action action)
+		{
+			lock (SyncRoot)
+				action();
+		}
+
+		internal static T RunSynchronized<T>(Func<T> action)
+		{
+			lock (SyncRoot)
+				return action();
+		}
+
 		public void SetTags(string filePath, ulong? frn, string[] tags)
+		{
+			RunSynchronized(() => SetTagsCore(filePath, frn, tags));
+		}
+
+		private void SetTagsCore(string filePath, ulong? frn, string[] tags)
 		{
 			if (FileTagsKey is null)
 				return;
@@ -94,6 +115,11 @@ public void SetTags(string filePath, ulong? frn, string[] tags)
 		}
 
 		public void UpdateTag(string oldFilePath, ulong? frn, string? newFilePath)
+		{
+			RunSynchronized(() => UpdateTagCore(oldFilePath, frn, newFilePath));
+		}
+
+		private void UpdateTagCore(string oldFilePath, ulong? frn, string? newFilePath)
 		{
 			if (FileTagsKey is null)
 				return;
@@ -122,6 +148,11 @@ public void UpdateTag(string oldFilePath, ulong? frn, string? newFilePath)
 		}
 
 		public void UpdateTag(ulong oldFrn, ulong? frn, string? newFilePath)
+		{
+			RunSynchronized(() => UpdateTagCore(oldFrn, frn, newFilePath));
+		}
+
+		private void UpdateTagCore(ulong oldFrn, ulong? frn, string? newFilePath)
 		{
 			if (FileTagsKey is null)
 				return;
@@ -151,10 +182,15 @@ public void UpdateTag(ulong oldFrn, ulong? frn, string? newFilePath)
 
 		public string[] GetTags(string? filePath, ulong? frn)
 		{
-			return FindTag(filePath, frn)?.Tags ?? [];
+			return RunSynchronized(() => FindTag(filePath, frn)?.Tags ?? []);
 		}
 
 		public IEnumerable<TaggedFile> GetAll()
+		{
+			return RunSynchronized(GetAllCore);
+		}
+
+		private IEnumerable<TaggedFile> GetAllCore()
 		{
 			var list = new List<TaggedFile>();
 
@@ -174,6 +210,11 @@ public IEnumerable<TaggedFile> GetAll()
 		}
 
 		public IEnumerable<TaggedFile> GetAllUnderPath(string folderPath)
+		{
+			return RunSynchronized(() => GetAllUnderPathCore(folderPath));
+		}
+
+		private IEnumerable<TaggedFile> GetAllUnderPathCore(string folderPath)
 		{
 			folderPath = folderPath.Replace('/', '\\').TrimStart('\\');
 			var list = new List<TaggedFile>();
@@ -194,6 +235,11 @@ public IEnumerable<TaggedFile> GetAllUnderPath(string folderPath)
 		}
 
 		public void Import(string json)
+		{
+			RunSynchronized(() => ImportCore(json));
+		}
+
+		private void ImportCore(string json)
 		{
 			if (FileTagsKey is null)
 				return;
@@ -218,6 +264,11 @@ public void Import(string json)
 		}
 
 		public string Export()
+		{
+			return RunSynchronized(ExportCore);
+		}
+
+		private string ExportCore()
 		{
 			var list = new List<TaggedFile>();
 
@@ -250,4 +301,4 @@ private void IterateKeys(List<TaggedFile> list, string path, int depth)
 			}
 		}
 	}
-}
+}
diff --git a/src/Files.App/Utils/FileTags/FileTagsHelper.cs b/src/Files.App/Utils/FileTags/FileTagsHelper.cs
@@ -19,12 +19,41 @@ public static class FileTagsHelper
 
 		public static string[] ReadFileTag(string filePath)
 		{
-			var tagString = Win32Helper.ReadStringFromFile($"{filePath}:files");
-			return tagString?.Split(',', StringSplitOptions.RemoveEmptyEntries) ?? [];
+			lock (FileTagsDatabase.SyncRoot)
+			{
+				var tagString = Win32Helper.ReadStringFromFile($"{filePath}:files");
+				return tagString?.Split(',', StringSplitOptions.RemoveEmptyEntries) ?? [];
+			}
 		}
 
 		public static async void WriteFileTag(string filePath, string[] tag)
 		{
+			bool result;
+			lock (FileTagsDatabase.SyncRoot)
+			{
+				result = WriteFileTagCore(filePath, tag);
+			}
+
+			if (!result)
+				await ShowTagWriteErrorAsync();
+		}
+
+		public static Task SetTagsAndWriteFileTagAsync(string filePath, ulong? frn, string[] tags)
+		{
+			bool result;
+			lock (FileTagsDatabase.SyncRoot)
+			{
+				// Update the registry index and ADS without allowing another tag operation to interleave.
+				GetDbInstance().SetTags(filePath, frn, tags);
+				result = WriteFileTagCore(filePath, tags);
+			}
+
+			return result ? Task.CompletedTask : ShowTagWriteErrorAsync();
+		}
+
+		private static bool WriteFileTagCore(string filePath, string[] tag)
+		{
+			var result = true;
 			var isDateOk = Win32Helper.GetFileDateModified(filePath, out var dateModified); // Backup date modified
 			var isReadOnly = Win32Helper.HasFileAttribute(filePath, IO.FileAttributes.ReadOnly);
 			if (isReadOnly) // Unset read-only attribute (#7534)
@@ -37,24 +66,7 @@ public static async void WriteFileTag(string filePath, string[] tag)
 			}
 			else if (ReadFileTag(filePath) is not string[] arr || !tag.SequenceEqual(arr))
 			{
-				var result = Win32Helper.WriteStringToFile($"{filePath}:files", string.Join(',', tag));
-				if (result == false)
-				{
-					await MainWindow.Instance.DispatcherQueue.EnqueueOrInvokeAsync(async () =>
-					{
-						ContentDialog dialog = new()
-						{
-							Title = Strings.ErrorApplyingTagTitle.GetLocalizedResource(),
-							Content = Strings.ErrorApplyingTagContent.GetLocalizedResource(),
-							PrimaryButtonText = "Ok".GetLocalizedResource()
-						};
-
-						if (ApiInformation.IsApiContractPresent("Windows.Foundation.UniversalApiContract", 8))
-							dialog.XamlRoot = MainWindow.Instance.Content.XamlRoot;
-
-						await dialog.TryShowAsync();
-					});
-				}
+				result = Win32Helper.WriteStringToFile($"{filePath}:files", string.Join(',', tag));
 			}
 			if (isReadOnly) // Restore read-only attribute (#7534)
 			{
@@ -64,47 +76,72 @@ await MainWindow.Instance.DispatcherQueue.EnqueueOrInvokeAsync(async () =>
 			{
 				Win32Helper.SetFileDateModified(filePath, dateModified); // Restore date modified
 			}
+
+			return result;
+		}
+
+		private static Task ShowTagWriteErrorAsync()
+		{
+			return MainWindow.Instance.DispatcherQueue.EnqueueOrInvokeAsync(async () =>
+			{
+				// Show the error dialog on the UI thread after releasing the file operation lock.
+				ContentDialog dialog = new()
+				{
+					Title = Strings.ErrorApplyingTagTitle.GetLocalizedResource(),
+					Content = Strings.ErrorApplyingTagContent.GetLocalizedResource(),
+					PrimaryButtonText = "Ok".GetLocalizedResource()
+				};
+
+				if (ApiInformation.IsApiContractPresent("Windows.Foundation.UniversalApiContract", 8))
+					dialog.XamlRoot = MainWindow.Instance.Content.XamlRoot;
+
+				await dialog.TryShowAsync();
+			});
 		}
 
 		public static void UpdateTagsDb()
 		{
 			var dbInstance = GetDbInstance();
 			foreach (var file in dbInstance.GetAll())
 			{
-				var pathFromFrn = Win32Helper.PathFromFileId(file.Frn ?? 0, file.FilePath);
-				if (pathFromFrn is not null)
+				lock (FileTagsDatabase.SyncRoot)
 				{
-					// Frn is valid, update file path
-					var tag = ReadFileTag(pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal));
-					if (tag is not null && tag.Any())
+					// Keep validation and updates for one item atomic with user tag changes.
+					var pathFromFrn = Win32Helper.PathFromFileId(file.Frn ?? 0, file.FilePath);
+					if (pathFromFrn is not null)
 					{
-						dbInstance.UpdateTag(file.Frn ?? 0, null, pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal));
-						dbInstance.SetTags(pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal), file.Frn, tag);
+						// Frn is valid, update file path
+						var tag = ReadFileTag(pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal));
+						if (tag is not null && tag.Any())
+						{
+							dbInstance.UpdateTag(file.Frn ?? 0, null, pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal));
+							dbInstance.SetTags(pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal), file.Frn, tag);
+						}
+						else
+						{
+							dbInstance.SetTags(pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal), file.Frn, []);
+						}
 					}
 					else
 					{
-						dbInstance.SetTags(pathFromFrn.Replace(@"\\?\", "", StringComparison.Ordinal), file.Frn, []);
-					}
-				}
-				else
-				{
-					var tag = ReadFileTag(file.FilePath);
-					if (tag is not null && tag.Any())
-					{
-						if (!SafetyExtensions.IgnoreExceptions(() =>
+						var tag = ReadFileTag(file.FilePath);
+						if (tag is not null && tag.Any())
 						{
-							var frn = GetFileFRN(file.FilePath);
-							dbInstance.UpdateTag(file.FilePath, frn, null);
-							dbInstance.SetTags(file.FilePath, frn, tag);
-						}, App.Logger))
+							if (!SafetyExtensions.IgnoreExceptions(() =>
+							{
+								var frn = GetFileFRN(file.FilePath);
+								dbInstance.UpdateTag(file.FilePath, frn, null);
+								dbInstance.SetTags(file.FilePath, frn, tag);
+							}, App.Logger))
+							{
+								dbInstance.SetTags(file.FilePath, null, []);
+							}
+						}
+						else
 						{
 							dbInstance.SetTags(file.FilePath, null, []);
 						}
 					}
-					else
-					{
-						dbInstance.SetTags(file.FilePath, null, []);
-					}
 				}
 			}
 		}
@@ -152,4 +189,4 @@ public static async Task<bool> RemoveTagsAsync(IEnumerable<ListedItem> items)
 			}
 		}
 	}
-}
+}
diff --git a/src/Files.App/Utils/Storage/Operations/FileOperationsHelpers.cs b/src/Files.App/Utils/Storage/Operations/FileOperationsHelpers.cs
@@ -1022,12 +1022,14 @@ private static void UpdateFileTagsDb(ShellFileOperations2.ShellFileOpEventArgs e
 						{
 							var tag = dbInstance.GetTags(sourcePath, null);
 
-							dbInstance.SetTags(destination, FileTagsHelper.GetFileFRN(destination), tag); // copy tag to new files
 							using var si = new ShellItem(destination);
 							if (si.IsFolder) // File tag is not copied automatically for folders
 							{
-								FileTagsHelper.WriteFileTag(destination, tag);
+								// Update the registry index and ADS together when copying a folder.
+								_ = FileTagsHelper.SetTagsAndWriteFileTagAsync(destination, FileTagsHelper.GetFileFRN(destination), tag);
 							}
+							else
+								dbInstance.SetTags(destination, FileTagsHelper.GetFileFRN(destination), tag); // copy tag to new files
 						}
 						else
 						{

diff --git a/src/Files.App/ViewModels/UserControls/SidebarViewModel.cs b/src/Files.App/ViewModels/UserControls/SidebarViewModel.cs
@@ -1438,7 +1438,6 @@ private Task<ReturnResult> HandleDriveItemDroppedAsync(DriveItem driveItem, Item
 		private async Task HandleTagItemDroppedAsync(FileTagItem fileTagItem, ItemDroppedEventArgs args)
 		{
 			var storageItems = await Utils.Storage.FilesystemHelpers.GetDraggedStorageItems(args.DroppedItem);
-			var dbInstance = FileTagsHelper.GetDbInstance();
 			var pathToTags = new Dictionary<string, string[]>();
 			foreach (var item in storageItems.Where(x => !string.IsNullOrEmpty(x.Path)))
 			{
@@ -1447,8 +1446,8 @@ private async Task HandleTagItemDroppedAsync(FileTagItem fileTagItem, ItemDroppe
 				{
 					filesTags = [.. filesTags, fileTagItem.FileTag.Uid];
 					var fileFRN = await FileTagsHelper.GetFileFRN(item.Item);
-					dbInstance.SetTags(item.Path, fileFRN, filesTags);
-					FileTagsHelper.WriteFileTag(item.Path, filesTags);
+					// Update the registry index and ADS as one synchronized operation.
+					_ = FileTagsHelper.SetTagsAndWriteFileTagAsync(item.Path, fileFRN, filesTags);
 					pathToTags[item.Path] = filesTags;
 				}
 			}