VSS_E_UNEXPECTED_PROVIDER_ERROR (Volume Shadow Copy issue)

Servosity Standard: All
Servosity Pro: All
OS: Windows

When performing a file backup, the following error message is received in the backup report:

Backup Logs  No.  Type  Timestamp  Backup Logs 1 Info YYYY/MM/DD hh:mm Start [ Windows platform (Test),Servosity Pro  5.x.x.x ] 2 Info YYYY/MM/DD hh:mm Start running pre-commands 3 ... ... ... *  Error  YYYY/MM/DD hh:mm [ERROR] VSS_E_UNEXPECTED_PROVIDER_ERROR

Notes:
Since a shadow copy cannot be created, the error above will usually result with the following error being flagged as well:

Backup Logs  No.  Type  Timestamp  Backup Logs *  ... ... ... *  Error  YYYY/MM/DD hh:mm [Error][Updated File] File="C:\Directory_Path\File" Error="The process cannot access the file because it is being used by another process."

This is a Microsoft Volume Shadow Copy issue.

Windows XP / Vista:
To resolve the issue, please re-register the Volume Shadow Copy Service. To do so, you could utilize the "RegisterVSS.bat" script available in ${Install-Home}\bin. Please also reboot the machine afterward.

Notes:
Please safely ignore the error message(s) displayed during the re-registration, as some of the DLL files are platform specific.

Windows 2003:
To resolve the issue, please follow the instructions below:

1. Please backup the registry key -
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\EventSystem\{26c409cc-ae86-11d1-b616-00805fc79216}\Subscriptions
2. Remove this registry key along with all its sub-keys
3. Reboot the machine

Although, it is not an official recommendation from Microsoft, this key will get recreated after the machine is restarted.