KB2964439 – Hyper-V VM Backup Leaves The VM In Locked State

A new KB article by Microsoft solves an issue where a Windows 8.1 Client Hyper-V or Windows Server 2012 R2 Hyper-V virtual machine backup leaves the VM in a locked state.


Consider the following scenario:

  • You’re running Microsoft System Center Data Protection Manager (DPM).
  • You start a backup job in DPM to back up Hyper-V virtual machines (VMs).

In this scenario, DPM sometimes leaves the VM stuck in the backup state (locked).

A supported hotfix is available from Microsoft Support. To apply this update, you must first install update 2919355 in Windows 8.1 or Windows Server 2012 R2.

8 thoughts on “KB2964439 – Hyper-V VM Backup Leaves The VM In Locked State”

  1. Is that Hotfix only for DPM trouble or maybe for Veeam too?
    Have last time see that in my Hyper-V Cluster but i don’t use DPM. I backup with Veeam.

    1. MSFT always describes backup issues in relation to DPM. But just about always, they are issues in Server. Note that the patch is a Windows patch, not a System Center patch.

  2. We had hyper-v guests locked in backup with differencing disks left over from the backup checkpoint. This update wanted a reboot on the host. We tried to drain the cluster node but the locked backups would not let the drain happen. We had to manually move all the guests that were in a good state to another node, then kill the VMMS.exe process on the host. After restarting VMMS.exe the differencing disks merged and we were able to pause the node & reboot.

  3. Does anyone have tried to install this update un HyperV 2012 R2 Free? I’m experiencing this issue with our Backup Solution (HP Data Protector) and when I try to install this hotfix it says “The Update is not applicable to your computer”

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