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Question

Backup failing VM with Error Code: [91:300] Description: Error creating virtual machine [VMNAME] snapshot

  • April 15, 2026
  • 1 reply
  • 4 views
Prateek Kumar
Novice
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Hi Team,

 

We are backing up a VM(hosted on MS HyperV) whose data disk is located on a SMB NAS File share.

We are getting below error.

Error Code: [91:300] Description: Error creating virtual machine [VMNAME] snapshot. 
Please check the virtual machine snapshot tree and the hosting volume for free space. 
[Checkpoint operation for 'VMNAME' failed. (Virtual machine ID 83A8CX27-…….A4) Checkpoint operation for 'VMNAME' was cancelled. (Virtual machine ID 83A8CX27-…….A4) 'VMNAME' could not initiate a checkpoint operation: The process cannot access the file because it is being used by another process. (0x80070020). (Virtual machine ID 83A8CX27-…….A4) 'VMNAME' could not create auto virtual hard disk \\IP\Host\VM_Disk_3714DCEE-3E97-4364-A678-897EF9FE93F0.avhdx: The process cannot access the file because it is being used by another process. (0x80070020). (Virtual machine ID 83A8CX27-…….A4)]. Source: commserve, Process: JobManager 

I have verified in the HyperV Host event viewer, it is throwing error “19100”

'VMNAME' background disk merge failed to complete: The process cannot access the file because it is being used by another process. (0x80070020). (Virtual machine ID 83A8CX27-…….A4).

So, my plan is to take downtime, merge the .avhdx disk with .vhdx.

Could you guys please check and confirm if we have any other alternate way or i can go ahead with my POA.

Thank you.

Thank you

1 reply

J
Vaulter
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  • Jace RossVaulter
  • Vaulter
  • April 16, 2026

Hi Prateek,

It seems like you’re well aware but checkpoint operations are requested by Commvault but handled by Hyper-V. In the vast majority of instances where a checkpoint fails, the issue resides within Hyper-V.

From a Commvault perspective there isn’t anything that can be done at the moment because the cleanup requests only occur at the end of a job.

You are on the right track though. Once the checkpoints have been merged, I would validate that you can manually create a checkpoint in hyper-V, then cleanup the manual checkpoint before attempting another backup.

I would also recommend investigating what might be holding the checkpoint preventing a merge. It could just be a stale Hyper-V process or it could be something like Antivirus which you’d want to exclude from scanning your VM repositories.

Cheers,

Jace Ross, Senior Technical SME
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