diff --git a/Duplicati/Library/AutoUpdater/UpdaterManager.cs b/Duplicati/Library/AutoUpdater/UpdaterManager.cs
index 20468fafd..29fcb3c25 100644
--- a/Duplicati/Library/AutoUpdater/UpdaterManager.cs
+++ b/Duplicati/Library/AutoUpdater/UpdaterManager.cs
@@ -116,7 +116,7 @@ namespace Duplicati.Library.AutoUpdater
         static UpdaterManager()
         {
             // Set the installation path
-            INSTALLATIONDIR = Util.AppendDirSeparator(Path.GetDirectoryName(Utility.Utility.getEntryAssembly().Location));
+            INSTALLATIONDIR = Util.AppendDirSeparator(Path.GetDirectoryName(Utility.Utility.getEntryAssembly().Location) ?? "");
 
             // Attempt to read the installed manifest file
             UpdateInfo? selfVersion = null;
diff --git a/Duplicati/Library/Main/Database/LocalRestoreDatabase.cs b/Duplicati/Library/Main/Database/LocalRestoreDatabase.cs
index 07972a364..3e2bba917 100644
--- a/Duplicati/Library/Main/Database/LocalRestoreDatabase.cs
+++ b/Duplicati/Library/Main/Database/LocalRestoreDatabase.cs
@@ -862,7 +862,7 @@ namespace Duplicati.Library.Main.Database
                                 ELSE ""Path""
                             END
                     ")
-                        .SetParameterValue("@Path", Util.AppendDirSeparator(System.IO.Path.GetPathRoot(Library.Utility.TempFolder.SystemTempPath)).Replace("\\", "/"))
+                        .SetParameterValue("@Path", Util.AppendDirSeparator(System.IO.Path.GetPathRoot(Library.Utility.TempFolder.SystemTempPath) ?? "").Replace("\\", "/"))
                         .ExecuteNonQueryAsync(token)
                         .ConfigureAwait(false);
                 }
diff --git a/Duplicati/Library/SourceProvider/Builtin/FileRestoreDestinationProvider.cs b/Duplicati/Library/SourceProvider/Builtin/FileRestoreDestinationProvider.cs
index a5c259541..4f6afcd4c 100644
--- a/Duplicati/Library/SourceProvider/Builtin/FileRestoreDestinationProvider.cs
+++ b/Duplicati/Library/SourceProvider/Builtin/FileRestoreDestinationProvider.cs
@@ -152,7 +152,7 @@ public class FileRestoreDestinationProvider(string mountedPath, bool allowRestor
         var targetpath = isDirTarget ? path.Substring(0, path.Length - 1) : path;
 
         // Make the symlink first, otherwise we cannot apply metadata to it
-        if (metadata.TryGetValue("CoreSymlinkTarget", out var k))
+        if (metadata.TryGetValue("CoreSymlinkTarget", out var k) && !string.IsNullOrWhiteSpace(k))
         {
             if (!allowRestoreOutsideTargetDirectory && !string.IsNullOrWhiteSpace(TargetDestination))
             {
diff --git a/proprietary/Office365/RestoreProvider/RestoreProvider.Group.cs b/proprietary/Office365/RestoreProvider/RestoreProvider.Group.cs
index bed3859f7..d469f3e16 100644
--- a/proprietary/Office365/RestoreProvider/RestoreProvider.Group.cs
+++ b/proprietary/Office365/RestoreProvider/RestoreProvider.Group.cs
@@ -623,7 +623,7 @@ public partial class RestoreProvider
                 }
 
                 // Remove the "/content.json" suffix to get the message path so replies can find it
-                var restoreMessagePath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath));
+                var restoreMessagePath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath) ?? "");
 
                 if (!_ignoreExisting)
                 {
diff --git a/proprietary/Office365/RestoreProvider/RestoreProvider.OneNote.cs b/proprietary/Office365/RestoreProvider/RestoreProvider.OneNote.cs
index 219f35db1..cda324c9b 100644
--- a/proprietary/Office365/RestoreProvider/RestoreProvider.OneNote.cs
+++ b/proprietary/Office365/RestoreProvider/RestoreProvider.OneNote.cs
@@ -256,7 +256,7 @@ public partial class RestoreProvider
                 var displayName = metadata.GetValueOrDefault("o365:Name") ?? metadata.GetValueOrDefault("o365:DisplayName") ?? "Restored Section Group";
 
                 // Find parent
-                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
 
                 string? parentId = null;
                 bool isNotebookParent = false;
@@ -310,7 +310,7 @@ public partial class RestoreProvider
                 var displayName = metadata.GetValueOrDefault("o365:Name") ?? metadata.GetValueOrDefault("o365:DisplayName") ?? "Restored Section";
 
                 // Find parent
-                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
 
                 string? parentId = null;
                 bool isNotebookParent = false;
@@ -360,7 +360,7 @@ public partial class RestoreProvider
             if (!filePath.EndsWith(".html", StringComparison.OrdinalIgnoreCase))
                 continue;
 
-            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(filePath.TrimEnd(Path.DirectorySeparatorChar)));
+            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(filePath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
             if (parentPath == null)
                 continue;
 
diff --git a/proprietary/Office365/RestoreProvider/RestoreProvider.SharePointLists.cs b/proprietary/Office365/RestoreProvider/RestoreProvider.SharePointLists.cs
index a2f71c438..b261ff328 100644
--- a/proprietary/Office365/RestoreProvider/RestoreProvider.SharePointLists.cs
+++ b/proprietary/Office365/RestoreProvider/RestoreProvider.SharePointLists.cs
@@ -240,7 +240,7 @@ public partial class RestoreProvider
 
                 while (true)
                 {
-                    var parentDir = Util.AppendDirSeparator(Path.GetDirectoryName(currentPath.TrimEnd(Path.DirectorySeparatorChar)));
+                    var parentDir = Util.AppendDirSeparator(Path.GetDirectoryName(currentPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
                     if (string.IsNullOrEmpty(parentDir)) break;
 
                     if (_restoredSharePointListMap.TryGetValue(parentDir, out var mappedListId))
@@ -307,7 +307,7 @@ public partial class RestoreProvider
 
                     // Determine parent ID
                     string parentId;
-                    var itemParentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+                    var itemParentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
 
                     try
                     {
@@ -441,7 +441,7 @@ public partial class RestoreProvider
         if (_restoredSharePointFolderMap.TryGetValue(currentPath, out var cachedId))
             return cachedId;
 
-        var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(currentPath.TrimEnd(Path.DirectorySeparatorChar)));
+        var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(currentPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
 
         // Safety check to prevent infinite recursion if we go above listPath
         if (string.IsNullOrEmpty(parentPath) || currentPath.Length <= listPath.Length)
diff --git a/proprietary/Office365/RestoreProvider/RestoreProvider.Tasks.cs b/proprietary/Office365/RestoreProvider/RestoreProvider.Tasks.cs
index ee6d4d157..d2b01dd05 100644
--- a/proprietary/Office365/RestoreProvider/RestoreProvider.Tasks.cs
+++ b/proprietary/Office365/RestoreProvider/RestoreProvider.Tasks.cs
@@ -138,7 +138,7 @@ public partial class RestoreProvider
                 var originalPath = task.Key;
 
                 // Find parent list
-                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
                 if (parentPath == null || !_restoredTaskListMap.TryGetValue(parentPath, out var listId))
                 {
                     Log.WriteWarningMessage(LOGTAG, "RestoreTaskListTasksMissingParent", null, $"Could not find parent list for task {originalPath}, skipping.");
@@ -213,7 +213,7 @@ public partial class RestoreProvider
                 var parentDir = Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)); // ChecklistItems
                 if (parentDir == null) continue;
 
-                var taskPath = Util.AppendDirSeparator(Path.GetDirectoryName(parentDir)); // TaskId
+                var taskPath = Util.AppendDirSeparator(Path.GetDirectoryName(parentDir) ?? ""); // TaskId
 
                 if (taskPath == null || !_restoredTaskMap.TryGetValue(taskPath, out var taskId))
                 {
@@ -227,7 +227,7 @@ public partial class RestoreProvider
                 var tasksDir = Path.GetDirectoryName(taskPath.TrimEnd(Path.DirectorySeparatorChar)); // Tasks
                 if (tasksDir == null) continue;
 
-                var listPath = Util.AppendDirSeparator(Path.GetDirectoryName(tasksDir)); // ListId
+                var listPath = Util.AppendDirSeparator(Path.GetDirectoryName(tasksDir) ?? ""); // ListId
 
                 if (listPath == null || !_restoredTaskListMap.TryGetValue(listPath, out var listId))
                 {
@@ -273,7 +273,7 @@ public partial class RestoreProvider
                 var parentDir = Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)); // LinkedResources
                 if (parentDir == null) continue;
 
-                var taskPath = Util.AppendDirSeparator(Path.GetDirectoryName(parentDir)); // TaskId
+                var taskPath = Util.AppendDirSeparator(Path.GetDirectoryName(parentDir) ?? ""); // TaskId
 
                 if (taskPath == null || !_restoredTaskMap.TryGetValue(taskPath, out var taskId))
                 {
@@ -285,7 +285,7 @@ public partial class RestoreProvider
                 var tasksDir = Path.GetDirectoryName(taskPath.TrimEnd(Path.DirectorySeparatorChar)); // Tasks
                 if (tasksDir == null) continue;
 
-                var listPath = Util.AppendDirSeparator(Path.GetDirectoryName(tasksDir)); // ListId
+                var listPath = Util.AppendDirSeparator(Path.GetDirectoryName(tasksDir) ?? ""); // ListId
 
                 if (listPath == null || !_restoredTaskListMap.TryGetValue(listPath, out var listId))
                 {
diff --git a/proprietary/Office365/RestoreProvider/RestoreProvider.cs b/proprietary/Office365/RestoreProvider/RestoreProvider.cs
index b6e2842ce..af6823ef3 100644
--- a/proprietary/Office365/RestoreProvider/RestoreProvider.cs
+++ b/proprietary/Office365/RestoreProvider/RestoreProvider.cs
@@ -878,7 +878,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
             // Determine parent folder ID
             // We assume the path structure reflects the hierarchy
             // If parent path is not in map, we assume it's the root (mailboxId)
-            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
             var parentId = mailboxId;
 
             if (parentPath != null && _restoredEmailFolderMap.TryGetValue(parentPath, out var mappedParentId))
@@ -939,7 +939,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
 
                 // Determine target folder
                 var targetFolderId = mailboxId;
-                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(emailSource.Key.TrimEnd(Path.DirectorySeparatorChar)));
+                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(emailSource.Key.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
                 if (parentPath != null && _restoredEmailFolderMap.TryGetValue(parentPath, out var mappedFolderId))
                 {
                     targetFolderId = mappedFolderId;
@@ -1068,7 +1068,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
         var restoreTarget = await DriveRestore.GetDefaultDriveAndFolder(cancel);
         if (!string.IsNullOrWhiteSpace(restoreTarget.FolderId))
         {
-            var rootFolderPath = Util.AppendDirSeparator(Path.GetDirectoryName(sortedFolders.First().Key.TrimEnd(Path.DirectorySeparatorChar)));
+            var rootFolderPath = Util.AppendDirSeparator(Path.GetDirectoryName(sortedFolders.First().Key.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
             _restoredDriveFolderMap.AddOrUpdate(rootFolderPath, restoreTarget.FolderId, (k, v) => v);
         }
 
@@ -1115,7 +1115,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
             }
 
             // Determine parent folder ID
-            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
             var parentId = defaultRootId;
 
             if (parentPath != null && (drivePath == null || parentPath.TrimEnd(Path.DirectorySeparatorChar) != drivePath.TrimEnd(Path.DirectorySeparatorChar)))
@@ -1217,7 +1217,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
                 }
 
                 // Determine parent folder ID
-                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
                 var parentId = defaultRootId;
 
                 if (parentPath != null && (drivePath == null || parentPath.TrimEnd(Path.DirectorySeparatorChar) != drivePath.TrimEnd(Path.DirectorySeparatorChar)))
@@ -1354,7 +1354,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
 
         // Group attachments by event path
         var attachments = GetMetadataByType(SourceItemType.CalendarEventAttachment)
-            .GroupBy(k => Util.AppendDirSeparator(Path.GetDirectoryName(k.Key.TrimEnd(Path.DirectorySeparatorChar))))
+            .GroupBy(k => Util.AppendDirSeparator(Path.GetDirectoryName(k.Key.TrimEnd(Path.DirectorySeparatorChar)) ?? ""))
             .ToDictionary(g => g.Key, g => g.ToList());
 
         var singles = new List<(string Path, GraphEvent Event)>();
@@ -1612,7 +1612,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
             }
 
             // Determine parent folder ID
-            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+            var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
             var parentId = defaultFolderId;
 
             if (parentPath != null && _restoredContactFolderMap.TryGetValue(parentPath, out var mappedParentId))
@@ -1672,7 +1672,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
 
                 // Determine target folder
                 var targetFolderId = defaultFolderId;
-                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
                 if (parentPath != null && _restoredContactFolderMap.TryGetValue(parentPath, out var mappedFolderId))
                 {
                     targetFolderId = mappedFolderId;
@@ -1779,7 +1779,7 @@ public partial class RestoreProvider : IRestoreDestinationProviderModule
 
                 // Determine target folder
                 var targetFolderId = defaultFolderId;
-                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)));
+                var parentPath = Util.AppendDirSeparator(Path.GetDirectoryName(originalPath.TrimEnd(Path.DirectorySeparatorChar)) ?? "");
                 if (parentPath != null && _restoredContactFolderMap.TryGetValue(parentPath, out var mappedFolderId))
                     targetFolderId = mappedFolderId;