If the activity log shows that creating an image from a SQL Server database has failed with the following error message:

An unexpected error occurred. The error code is logged in the error log file. (VssUnexpectedErrorException)

Check that all the necessary components of the Volume Shadow Copy Service are enabled in Windows services on the source SQL Server machine.

• The Volume Shadow Copy service must be enabled 
• A shadow copy provider must also be enabled. This is normally the Microsoft Software Shadow Copy Provider service, unless you are using a different shadow copy provider.

You can check that the Volume Shadow Copy Service is correctly configured by running the following PowerShell command in an admin PowerShell session on the machine which hosts the source SQL Server instance and SQL Clone agent:

vssadmin list shadows

The command should execute without error.