I have a script that runs every day to perform a SharePoint differential backup, but every time it runs, i get this error:

“Cannot perform a differential backup for database “SharePoint_Config”, because a current database backup does not exist. Perform a full database backup by reissuing BACKUP DATABASE, omitting the WITH DIFFERENTIAL option. BACKUP DATABASE is terminating abnormally.”

It seems that the problem is on the “SQL Server VSS Writer” service. Stopping the “SQL Server VSS Writer” should stop snapshot backups cause problems for your SQL backups.

Only stop this service if you are not using it for backup/restore through VSS.

The SQL Writer Service provides added functionality for backup and restore of SQL Server through the Volume Shadow Copy Service framework.