Kaseya Backup: VSS troubleshooting guide


Use this article to troubleshoot when backups fail because Volume Shadow copy (VSS) snapshot creation fails.

The following backup errors may be related to VSS failure: -

- Failed to create volume snapshot

- Failed to read the snapshot

- Failed to create snapshot bitmap

- Failed to start creating the volume snapshot

- The device is not ready



There are many possible causes, but problems usually fall into one of these categories

  • Acronis errors
  • Windows errors - there is a problem with the VSS service
  • VSS writer errors - there is a problem with an application vendor VSS writer
  • system resource issues (in this case the problem may be intermittent)



Use the following troubleshooting steps to investigate the issue: -


1) to validate if a backup failure is definitely related to VSS, attempt backup of the same data without VSS enabled

  • go to Schedule Volumes or Schedule Folders, un-check "Enable VSS support", apply to the agent in question
  • run another backup
  • NB - if the agent machine has VSS-dependent applications running, their database may not be backed up in consistent state if VSS is not enabled. In this case, disabling VSS should only considered as a troubleshooting step and potential workaround, not a solution.

2) check if required Windows services are enabled and running on the backup agent machine

Go to Start -> Run -> services.msc. The following Windows services should be enabled and set to Manual start: -

  • Microsoft Software Shadow Copy Provider
  • Volume Shadow Copy

Following Windows service should be running and set to Automatic start: -

  • COM+ Event System service

3) check if VSS snapshot can be created directly from Windows on the backup agent machine

Server OS: -

  • Go to My Computer -> Right click on any of internal volumes listed -> Configure Shadow Copies
  • Select each volume you are trying to back up and click on Create shadow copy to confirm that there is sufficient free space on each volume. Otherwise set up the storage area for the volume.
  • You can also use the vssadmin utility to run this check and create,increase or relocate the shadow storage

Windows Vista and later workstations: -

  • Go to Control Panel -> System - >System protection
  • Select each volume you are trying to back up and click on "Create" button to create restore point. If necessary, configure protection for the volume and increase the size of the storage.

Windows XP: -

  • To check that the volume has enough free space and force the shadow copy creation, run the ntbackup utility and backup some data from the volume you want to check, checking the shadow copy creation. Run cmd and enter ntbackup.exe.
  • In case you need to create or increase the size of the storage, go to Control Panel -> System -> System restore and configure space for the storage.

4) check for errors in Windows VSS service

  • Go to Start -> Run -> eventvwr.msc. Navigate to Windows Logs -> Application and check for error messages related to VSS service. Search for solution in Microsoft Support articles, for example this TechNet arcticle

5) ensure VSS writers are enabled and in stable state

a. log onto backup agent machine as administrator level user, go to Start -> Run -> cmd, execute the command "vssadmin list writers"
b. check state of all writers, if they are all reported as "stable", skip to "FURTHER INVESTIGATION" section

6) investigate any VSS writer errors

a. if a writer is in "retryable" error state, restart the Windows service associated with the writer and retry the backup.

b. if the backup still fails, temporarily stop and disable the writer's service and retry the backup again.  If backup now succeeds, the writer causes the failure and issue should be addressed to the vendor of the writer.



If the problem could not be resolved using the above steps, please provide Kaseya Support with the following information: -


1) XML log of failed backup (click on "failed" hyper-link from Backup Logs page)

2) "Acronis Info" report (acronisinfo.zip) 

3) snapAPI logs 

4) VSS logs 

5) detailed results of the above troubleshooting steps

- does non-VSS enabled backup complete without error?

- can VSS snapshot be created from Windows?

- were any VSS service errors found?

- were any VSS writer errors found?

6) if you have provided access to VSA web interface, please state affected agent IDs



Kaseya Backup (KBU) - all versions

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