Hyper-V Instance Backup Fails due to Inability to Remove Temporary Checkpoint


In rare occurrence it could happen that a specific Hyper-V instance fails to be backed-up due to accummulation of invalid temporary checkpoints that cannot be deleted.

The following error could be reported for a failing backup plan:

WMI Error (Code 1914) WMI job failed Reason Job Failed: "Error Code: '32779'

Alongside the diagnostic log records for a failing plan, similar to the ones below:

2024-05-05 12:48:40,000 [VM] [1] INFO - Deleting old checkpoints with name:'CBB temporary snapshot for plan XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXX' 2024-05-05 12:48:41,000 [VM] [1] INFO - Removing virtual machine checkpoint: CBB temporary snapshot for plan XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXX 2024-05-05 12:48:42,000 [VM] [1] ERROR - Job failed : ''. Error code: '32779'. 2024-05-05 12:48:43,000 [SERV] [1] ERROR - Error occurred on virtual machine backup: [INSTANCE_NAME]

In case the Hyper-V instance with a problemtic backup, when observed in Hyper-V Manager, has the following properties:

  • A tree of old (relative to the backup date) temporary checkpoints that cannot be manually deleted due to absence of corresponding AVHD or AVHDX files (referential example is shown below):

  • No redundant AVHD or AVHDX files with creation / modification dates corresponding with the aforementioned old temporary checkpoints.

  • Persistence of the issue past maintenance reboot of the Hyper-V host server.

Then the following solution below should be considered.


If manual removal of broken temporary checkpoints cannot be performed, manual sequential merging of all AVHD (or AVHDX) files of the problematic Hyper-V instance is required to properly address and resolve the issue.