diff --git a/package.json b/package.json
index de693fb..4993532 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "my-weekly-todo-list",
-  "version": "1.57.2",
+  "version": "1.57.3",
   "description": "A web-based weekly task management application that organizes to-dos and calendar events in a single, intuitive weekly view",
   "main": "index.js",
   "scripts": {
diff --git a/src/app/api/tasks/sync/route.ts b/src/app/api/tasks/sync/route.ts
index 91775d6..396782a 100644
--- a/src/app/api/tasks/sync/route.ts
+++ b/src/app/api/tasks/sync/route.ts
@@ -206,7 +206,20 @@ export async function GET(req: NextRequest) {
                             }
                         }
                     } catch (listError: any) {
-                        if (listError?.code === 429 || listError?.status === 429) {
+                        if (listError?.code === 404 || listError?.status === 404) {
+                            console.warn(`Google Tasks list ${listId} not found (deleted?), cleaning up local references`);
+                            // Soft-delete local tasks linked to this deleted list
+                            const result = await prisma.task.updateMany({
+                                where: { userId: user.id, externalProvider: 'google', externalListId: listId, deletedAt: null },
+                                data: { deletedAt: new Date() },
+                            });
+                            deleted += result.count;
+                            // Unlink the synced someday list
+                            await prisma.somedayList.updateMany({
+                                where: { userId: user.id, externalProvider: 'google', externalId: listId },
+                                data: { externalId: null, externalProvider: null },
+                            });
+                        } else if (listError?.code === 429 || listError?.status === 429) {
                             console.warn(`Google Tasks quota exceeded for list ${listId}, skipping`);
                         } else {
                             console.error(`Error syncing Google list ${listId}:`, listError);