Getting Error while syncing Folder for Microsoft Exchange

I am getting 404 Error while syncing folders. Using Ver 6.0.24316.0

9:02:31 AM   MailExceptions.OperationException: Synchronizing folder list failed due to the following error: The remote server returned an error: (404) Not Found. —> System.Net.WebException: The remote server returned an error: (404) Not Found.