Azure Confidential VM Backup (Preview) fails after V5 to V6 upgrade - Error: Backup is not available in this region

GinaLiu-4648 0 Reputation points
2026-11-06T00:44:42.4233333+00:00

I am trying to use the preview feature for Confidential VM backup. I upgraded my VM from V5 to V6 and successfully registered the RestorePointSupportForConfidentialVMV2 feature in my subscription. However, manual backups still fail after 7+ hours.

Azure Support closed my ticket and directed me here, stating they lacked specific error codes and environment details. Here is the complete diagnostic data that addresses all their "unknowns":

  1. Exact Error Details (from the failed backup job):

Error Code: UserErrorConfidentialVMBackupIsNotAvaliableInThisRegion

Activity ID: 58ef397a-36a9-4483-b95e-631e1e5a36a2

Error Message: Confidential VM backup is not available in this region

Additional Details: BadRequest : This region does not support creation of Restore Points of a Virtual Machine with 'ConfidentialVM' security type.

  1. Protection & Vault Status:

Protection Status: Failed / Initial backup pending.

Soft-delete Status: The VM is NOT in the soft-deleted items list. There are no duplicate or conflicting protection items.

Recovery Points: None (latest restore point is blank).

  1. VM & Extension Status (Possible Root Cause):

VM State: Running

Guest Agent: Ready (version 2.16.0.2)

Snapshot Extension: Missing. The Microsoft.Azure.RecoveryServices.VMSnapshotLinux extension is NOT listed in the VM's Extensions + applications blade.

  1. Environment & Comparison:

Location: West US

VM Size: Standard_DC2eds_v6 (Upgraded from DC2ads_v5)

Security Type: ConfidentialVM (Platform Managed Key)

I have another VM in the exact same region (West US), with the exact same JSON security profile, VM size, and OS, which backs up perfectly. The only difference is they are in different subscriptions (though both have the preview feature registered).

Could the Product Group please investigate why the backup service still thinks this region/VM is unsupported despite the V6 upgrade and preview registration? Is there a provisioning failure preventing the VMSnapshotLinux extension from installing on this specific VM?

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  1. Rukshan edirisinghe 2,365 Reputation points
    2026-11-06T02:06:29.4833333+00:00

    Hi @GinaLiu-4648

    Your comparison is the key clue. Microsoft's Confidential VM backup doc says the public preview is available in all Azure public regions and supports v6-series VMs, so West US with DC2eds_v6 is fine. Since an identical VM in another subscription backs up, the "region not supported" error is most likely coming from a subscription-level setting in the failing subscription, not from the region or the VM.

    I'd compare the two subscriptions on these points:

    1. Feature state, not just registration. Run Get-AzProviderFeature -FeatureName RestorePointSupportForConfidentialVMV2 -ProviderNamespace Microsoft.Compute in both. It must show Registered, not Registering.
    2. Re-register the provider. After a feature flag is approved, the provider needs a refresh before it takes effect: Register-AzResourceProvider -ProviderNamespace Microsoft.Compute. Wait a few minutes after it finishes.
    3. Look for the opt-out flag. The doc warns that backup and restore fail if the CVM v2 opt-out feature flag is enabled for the subscription. List the Confidential-related features in both subscriptions and compare: Get-AzProviderFeature -ProviderNamespace Microsoft.Compute -ListAvailable | Where-Object FeatureName -like '*Confidential*' | Format-Table FeatureName, RegistrationState. Anything registered only in the failing one is a strong suspect.
    4. Re-protect after the fix. If protection was configured while the VM was still v5, choose Stop backup with Retain backup data, then configure backup again, so the service evaluates the VM as v6. Retaining the data keeps any existing recovery points safe.

    The missing VMSnapshotLinux extension is most likely a symptom rather than the cause, since the job is rejected before the snapshot stage.

    What does the feature comparison in step 3 show between the two subscriptions?

    If the backup completes after this, please consider accepting it as the answer. If both subscriptions match and it still fails, let me know and I'll be happy to keep helping.

    Reference:

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