Here’s some info specifically about the VSS issues in Acronis. 

VSS errors are either a failure of the VSS writer on the machine, or an issue with Acronis VSS.

– Check local VSS writers on a machine by running:
“vssadmin list writers” at a command prompt on the machine.  Look for anything that doesn’t say “State: Stable”.  Anything other than Stable and you will need to correct it before backups will be successful.  Usually a restart of the service, or a reboot of the machine will correct it. 

If that doesn’t work, then there is an issue on the machine that will need to be addressed to get the VSS Writers to a Stable status.

– Make sure all of your backup jobs are set to use the MS VSS writers. Don’t let it automatically choose the VSS,  We have seen issues when using the Auto setting.  This setting is under the “Options” tab of the backup profile, “Volume Shadow Copy Service”.  Not checking any box will cause the system to “pick something”.