Microsoft Azure Backup for Server not backing up

Question

Microsoft Azure Backup for Server not backing up

Olmec Systems 0

We have four servers not backing up in MABS. Here is the error: Type: Consistency check

Status: Failed

Description: DPM encountered error from VMware while trying to get ChangeTracking information. Server - 10.1.10.240 ErrorCode - FileFaultFault (ID 33621 Details: Internal error code: 0x80990EF3)

Thanks.

Suchitra Suregaunkar 13,785 Reputation points Microsoft External Staff Moderator

2026-04-22T17:15:56.9366667+00:00
Hello Olmec Systems

Which version of MABS and VMware/vCenter are you running?

Do those VMs have snapshots or were they recently migrated?

Are any disks marked “Independent” or “Multi-writer”?

Did you recently upgrade VMware tools or change datastore paths?

Thanks,
Suchitra.
Suchitra Suregaunkar 13,785 Reputation points Microsoft External Staff Moderator

2026-04-24T14:58:05.2666667+00:00
Hello Olmec Systems

It looks like your MABS consistency checks are failing for those VMware-backed VMs with the FileFaultFault (ID 33621 / 0x80990EF3). That specific error usually means MABS can’t read the VMware change tracking (CTK) info. Here’s what you can try:

Reset the VMware change tracking (CTK) on each affected VM – In vSphere, edit each VM’s Advanced Configuration and delete the CTK file entries so they get rebuilt on next backup.

Verify no “Independent” or “Multi-writer” disks are attached – MABS relies on VMware snapshots—those disk types bypass snapshots and break CTK.

In MABS, stop protection for the affected VMs, then reprotect them using the Refresh button – This forces MABS to re-discover the VM and rebuild the disk-backup replica.

Once protection is reconfigured, run a manual consistency check on each VM – That should rebuild the replica and clear the FileFaultFault error.

References:

• Troubleshoot Azure Backup Server – Online recovery point creation jobs for VMware VM fail https://learn.microsoft.com/azure/backup/backup-azure-mabs-troubleshoot#online-recovery-point-creation-jobs-for-vmware-vm-fail

• Troubleshoot Azure Backup Server – Basic backup troubleshooting https://learn.microsoft.com/azure/backup/backup-azure-mabs-troubleshoot#backup

Thanks,

Suchitra.
Suchitra Suregaunkar 13,785 Reputation points Microsoft External Staff Moderator

2026-04-24T14:58:39.54+00:00

Hello Olmec Systems

Could you please let us know if the comment above resolved your issue? If you need any further assistance, feel free to reach out, we're always here to support you.

If you found the comment helpful, please consider clicking "Upvote it."

Thanks,
Suchitra.

1 answer

Your answer

Suchitra Suregaunkar 13,785 Reputation points Microsoft External Staff Moderator

2026-04-22T17:15:56.9366667+00:00

Hello Olmec Systems

Which version of MABS and VMware/vCenter are you running?

Do those VMs have snapshots or were they recently migrated?

Are any disks marked “Independent” or “Multi-writer”?

Did you recently upgrade VMware tools or change datastore paths?

Thanks,
Suchitra.
Suchitra Suregaunkar 13,785 Reputation points Microsoft External Staff Moderator

2026-04-24T14:58:05.2666667+00:00

Hello Olmec Systems

It looks like your MABS consistency checks are failing for those VMware-backed VMs with the FileFaultFault (ID 33621 / 0x80990EF3). That specific error usually means MABS can’t read the VMware change tracking (CTK) info. Here’s what you can try:

Reset the VMware change tracking (CTK) on each affected VM – In vSphere, edit each VM’s Advanced Configuration and delete the CTK file entries so they get rebuilt on next backup.

Verify no “Independent” or “Multi-writer” disks are attached – MABS relies on VMware snapshots—those disk types bypass snapshots and break CTK.

In MABS, stop protection for the affected VMs, then reprotect them using the Refresh button – This forces MABS to re-discover the VM and rebuild the disk-backup replica.

Once protection is reconfigured, run a manual consistency check on each VM – That should rebuild the replica and clear the FileFaultFault error.

References:

• Troubleshoot Azure Backup Server – Online recovery point creation jobs for VMware VM fail https://learn.microsoft.com/azure/backup/backup-azure-mabs-troubleshoot#online-recovery-point-creation-jobs-for-vmware-vm-fail

• Troubleshoot Azure Backup Server – Basic backup troubleshooting https://learn.microsoft.com/azure/backup/backup-azure-mabs-troubleshoot#backup

Thanks,

Suchitra.
Suchitra Suregaunkar 13,785 Reputation points Microsoft External Staff Moderator

2026-04-24T14:58:39.54+00:00

Hello Olmec Systems

Could you please let us know if the comment above resolved your issue? If you need any further assistance, feel free to reach out, we're always here to support you.

If you found the comment helpful, please consider clicking "Upvote it."

Thanks,
Suchitra.

Answer 1

The error DPM encountered an error from VMware while trying to get ChangeTracking information. ErrorCode - FileFaultFault (ID 33621) is a known issue when Microsoft Azure Backup Server (MABS) backs up VMware VMs. It indicates a problem with VMware Changed Block Tracking (CBT) or the VM configuration.

To troubleshoot and resume backups for the affected servers, follow these steps on the VMware side and then in MABS:

Reset VMware Change Tracking (CTK/CBT) for the affected VMs
- On the VMware host/vCenter, reset CTK for each VM that is failing.
- After resetting CTK, power-cycle the VM as required by VMware guidance so that new CTK files are created.
Verify that no independent disks are attached
- In the VM settings in vCenter, check each virtual disk.
- Ensure no disk is configured as an independent disk (independent disks are not supported for application-consistent/CBT-based backups).
- If any disk is independent, change it to a supported mode or exclude that VM/disk from protection as appropriate.
Reprotect the VMs in MABS
- In the MABS console, open the Protection Group that contains the affected VMware VMs.
- Use Modify protection group and select Refresh on the VMware selection page so MABS re-reads the VM configuration from vCenter.
- Re-add the VMs if necessary and complete the wizard.
Run a Consistency Check (CC)
- In the MABS console, right‑click each affected data source (VM) and select Perform consistency check.
- Wait for the CC to complete successfully; this validates and repairs the replica before the next backup.

If backups still fail after these steps, repeat the CTK reset and ensure there are no remaining configuration issues on the VMware side (such as stale CTK files or unsupported disk types), then refresh and reprotect again in MABS.

References:

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Microsoft Azure Backup for Server not backing up

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