Snapshots fail and upon investigation of the Windows OS application log the error code 8193 is present - containing the detail similar to below:
Volume Shadow Copy Service error: Unexpected error calling routine RegOpenKeyExW(-2147483646,SYSTEM\CurrentControlSet\Services\VSS\Diag,...). hr = 0x80070005, Access is denied.
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.
Inspection of the detailed tab of the event log entry will show information about the process that generated the error. Take note of the user mentioned after the “- User: Name:” portion of the bytes (typically this may be the NETWORK SERVICE.
To resolve this error,