Foxmarks: Error: Failed to parse sync file

From Foxcloud Wiki

If you get this message, it means that Foxmarks was unable to retrieve a synchronization file from the server, or the synchronization file itself has become corrupted.

This can happen if you cancel synchronization while Foxmarks is uploading the synchronization file.

To remedy the situation, open the Foxmarks control panel (from Firefox, Bookmarks -> Foxmarks...), go to the Other tab and select Upload Now -- this will upload a new synchronization file to replace the damaged one.