When VSS creates a shadow copy the following VSS error 8193 is logged to the Windows Application log:
Volume Shadow Copy Service error: Unexpected error calling routine ConvertStringSidToSid(S-1-5-21-1594437928-2122080341-1231754661-4183.bak). hr = 0x80070539, The security ID structure is invalid.
Windows Registry Disclaimer:
Quest does not provide support for problems that arise from improper modification of the registry. The Windows registry contains information critical to your computer and applications. Make sure you back up the registry before modifying it. For more information on the Windows Registry Editor and how to back up and restore it, refer to Microsoft Article ID 256986 “Description of the Microsoft Windows registry” at Microsoft Support.