Veeam Backup error related to CBT


Backup jobs keep failing or taking longer time to finish due to failed to create change tracking time stamp for virtual disk file.

Error:CBT error


We have restarted each hyper-v host.

updated hyper-v integration tools on hyper-v hosts

migrated few VMs from the Volume1 to new Volume 3

still no luck

I have found the Veeam article , which helped to resolve our issue.

To reset changed block tracking, we have performed the following steps from article:

  • Select the option to disable changed block tracking on all Hyper-V hosts in the cluster.  To do this, right-click on each host in the cluster, select Manage Volumes and then check the box to disable changed block tracking.

User-added image

  • Run sc stop VeeamFCT, in an elevated command prompt, on each Hyper-V host in the cluster to ensure the CBT service is stopped.
  • Find, export and then delete the following registry key on all Hyper-V hosts in the cluster:  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VeeamFCT\Parameters\CTDB
  • Go back to the Manage Volumes for each host and uncheck the disable changed block tracking option.  Try the job after this.  Allow a couple of job runs before ensuring CBT is working.
  • If the issue persists, reboot each Hyper-V host in the cluster.  This will typically involve migrating VMs from one host to another and rebooting the host once it does not own any VMs.  Repeat these steps for all Hyper-V hosts in the cluster.

Hope the above steps helps.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s