Azure migrate to managed disks but "Operation is not allowed since VM has an extension in failed state"

Question

Azure migrate to managed disks but "Operation is not allowed since VM has an extension in failed state"

Moya 0

We have received an email saying we need to migrate our Azure VMs to managed disks.

However, when we try to migrate to managed disks, we get told:

"Operation is not allowed since VM has an extension in failed state"

There are several extensions, the most troublesome seems to be OmsAgentForLinux. We never installed this nonsense, it seems to have been added automatically; we just want it gone.

We tried uninstalling from the azure portal, but it timed out and said it did not uninstall successfully. Ever since it has been hanging in state "Transitioning."

We have then also tried out the purge script directly on the affected VMs; the purge script executed successfully, but still the portal shows OmsAgentForLinux as Transitioning and prevents us from migrating to managed disks.

We do not actually want managed disks, we are just migrating because we got an email saying that we need to; but we also do not want any of these extensions that are now blocking us from migrating.

How can we get rid of them?

Ankit Yadav 13,215 Reputation points Microsoft External Staff Moderator

2026-03-31T09:58:33.58+00:00
Hello Moya,

The error “Operation is not allowed since VM has an extension in failed state” means that Azure has detected a problem with one of the virtual machine extensions, and because of that, it is blocking the disk migration.

Even if the Azure portal shows all extensions as “Provisioning succeeded,” Azure also checks the internal system status of the VM. Sometimes, an extension may appear healthy in the portal but is actually in a failed or incomplete state behind the scenes. When this happens, operations like migrating to managed disks are not allowed.

In your case, the OmsAgentForLinux extension is stuck in a “Transitioning” state. This usually happens when the extension was installed automatically (for example, by monitoring tools) and did not uninstall properly. Removing the agent from inside the virtual machine does not fully fix the issue because Azure still keeps a record of the extension.

To resolve this, the extension needs to be removed from the Azure VM itself.

Follow these steps:

Stop and deallocate the virtual machine This is required before making changes to extensions or disks.

az vm deallocate --resource-group --name

Remove the extension from VM and then try deleting the extension using the following command:
az vm extension delete --resource-group --vm-name --name OmsAgentForLinux

Verify the extension is removed Run this command to confirm:
az vm extension list --resource-group --vm-name

Once the extension is fully removed or shows a healthy state, you should be able to retry the migration successfully.

Note: Extensions like OmsAgentForLinux are not required for disk migration. You can safely remove them if they are causing issues.

While you may prefer not to use managed disks, Azure is retiring out unmanaged disks. Migrating to managed disks is necessary to continue using the virtual machine without future disruptions.

References:

https://learn.microsoft.com/en-us/azure/virtual-machines/extensions/troubleshoot

https://learn.microsoft.com/en-us/powershell/module/az.compute/remove-azvmextension?view=azps-15.4.0

https://learn.microsoft.com/en-us/cli/azure/vm/extension?view=azure-cli-latest#az-vm-extension-delete

https://learn.microsoft.com/en-us/azure/virtual-machines/windows/convert-unmanaged-to-managed-disks
Moya 0 Reputation points

2026-03-31T23:45:41.4833333+00:00

Hi Ankit,

Thank you for the answer.

Unfortunately, when we follow your commands, we do run into trouble:

When we run az vm deallocate and afterwards az vm extension delete we get told:

Message: Cannot modify extensions in the VM when the VM is not running.

When we start the VM again and run az vm extension delete we get told, after a very long time - maybe half an hour:

Message: Provisioning of VM extension OmsAgentForLinux has timed out. Extension provisioning has taken too long to complete. The extension did not report a message. More information on troubleshooting is available at https://aka.ms/VMExtensionOMSAgentLinuxTroubleshoot

We have also tried the purge script already that is offered at the link embedded in the message (the purge script says it ran perfectly, all purged... but still it remains in the portal and prevents the migration to managed disks.)

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Moya 0 Reputation points

2026-03-31T23:45:41.4833333+00:00

Hi Ankit,

Thank you for the answer.

Unfortunately, when we follow your commands, we do run into trouble:

When we run az vm deallocate and afterwards az vm extension delete we get told:

Message: Cannot modify extensions in the VM when the VM is not running.

When we start the VM again and run az vm extension delete we get told, after a very long time - maybe half an hour:

Message: Provisioning of VM extension OmsAgentForLinux has timed out. Extension provisioning has taken too long to complete. The extension did not report a message. More information on troubleshooting is available at https://aka.ms/VMExtensionOMSAgentLinuxTroubleshoot

We have also tried the purge script already that is offered at the link embedded in the message (the purge script says it ran perfectly, all purged... but still it remains in the portal and prevents the migration to managed disks.)

Answer 1

Hello Moya,

Thank you for getting back to me.

I tried to reproduce the issue but for me the extension was installed successfully and thus was removed successfully both from Portal UI and via Az-cli commands.
Can you please try to re-provision the extension, this will get the extension in successful provisioning state then you can easily remove the extension?

Steps to provision the extension:

Create a Log Analytics Work-space (let's say test-oms-workspace) in same region as your VM.
Get the work-space id and the workspace key using below commands respectively.

az monitor log-analytics workspace show --resource-group <rg> --workspace-name test-oms-workspace --query customerId -o tsv   

az monitor log-analytics workspace get-shared-keys --resource-group <rg> --workspace-name test-oms-workspace --query primarySharedKey -o tsv

Install extension using below command,

az vm extension set \
--resource-group <rg-name> \
--vm-name <vm-name> \
--name OmsAgentForLinux \
--publisher Microsoft.EnterpriseCloud.Monitoring \
--version 1.13.0 \
--settings '{"workspaceId":"<id>"}' \
--protected-settings '{"workspaceKey":"<key>"}'

Goto to VM portal and see if the extension is in successful provisioning state or not. If yes try to delete it, if not, let us know about it.

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Azure migrate to managed disks but "Operation is not allowed since VM has an extension in failed state"

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