1453 - VSS backups fail if Sophos antivirus is installed

Symptom

VSS backups fail randomly if Sophos antivirus is installed on the machine.

Cause

The way in which the Sophos endpoint agent writes to the Windows registry causes the Volume Shadow Copy Service (VSS) to time out, which causes the backup to fail.

Solution

To resolve, follow the steps provided by Sophos. See also this article from Microsoft's knowledge base.