Hyper-V Backups for VHDX Disks Might Fail on Microsoft Windows Server 2012

Article ID: HPV0002 After installing the update package in Microsoft KB 3000853, some virtual machine backups fail.

Symptom

This update package causes issues for backups because Volume Shadow Copy Service (VSS) leaves VHDX disks in an inconsistent state. As a result, inconsistent disks are staged to the job results folder and virtual machine backups fail when the job results folder runs out of space. 

Reported events can indicate errors such as the following:

  • Unable to open virtual disk
  • Re-staging virtual disk to temporary location and attempting reopen again

This issue can cause the following:

  • An increase in backup time, even if there is sufficient space in the job results folder. 
  • Problems on the operating system disk, if free space is low and the job results folder is on the operating system disk. 

Cause

This issue occurs after installing the optional update package in Microsoft November 2014 update rollup for Windows RT, Windows 8, and Windows Server 2012 (KB 3000853). 

This issue affects VSS application backups for virtual machines on Microsoft Windows Server 2012. Any VSS-aware applications might be affected. 

Resolution

To resolve this issue, apply Microsoft hotfix as described in Backup task fails with a time-out error in Windows Server 2012 or Windows Server 2008 R2