ATTENTION 1st January, 2022: v7 officially End-of-Life [details]
Exclusively opened file on a local hard disk cannot be backed up.
Many underlying components in the operating system may come into play during the backup process, to cause the VSS error. This article offers a guideline to troubleshoot errors related to Volume Shadow Copy.
Below are the steps that you should follow to troubleshoot errors related to Volume Shadow Copy: (
The steps may vary depending on the operating system):