I am Dale Hayter, a Microsoft and VMware certified Technical Consultant.

My blog has been built up over the years from my experience of working on an IT helpdesk and also from being out on-site.

Veeam – Unable to release guest – A VSS critical writer has failed, NTDS

A common issue I have come across with Veeam is that sometimes you get the error message shown below when backing up a domain controller:-

Unable to release guest. Error: Unfreeze error: [Backup job failed. Cannot create a shadow copy of the volumes containing writer's data.
A VSS critical writer has failed. Writer name: [NTDS]. Class ID: [{b2014c9e-8711-4c5c-a5a9-3cf384484757}]. Instance ID: [{850442eb-2b2e-47c2-b6a6-a8abfdba0b31}]. Writer's state: [VSS_WS_FAILED_AT_POST_SNAPSHOT]. Error code: [0x800423f4].]

To cure the problem check for a failed NTDS Writer by doing the following :

Run an elevated command prompt and type

vssadmin list writers

You should see the results below


If it says failed then reboot the server and then try the backup again.

If the backup still fails then open an elevated command prompt again and type


Followed by

automount enable

Try the backup again.

Still failing then this last step normally resolves the issue. Enter the registry and go to the following key

HKEY_Local_Machine\Software\Microsoft\Windows NT\CurrentVersion\ProfileList

In there your see a whole load of GUID’s. Delete all the ones with .bak at the end. If your nervous then take a backup of them before.


Reboot the server and all should be good.

Source : Veeam KB1697