Unable to create A Virtual Machine scale set in West US 2 region(spec: 2025-datacenter-azure-edition and Standard_DC4as_v6)

Hello Nishitha,

hank you for sharing the detailed information. The behavior you are observing is expected and is related to how Azure enforces patching requirements for Hotpatch-enabled images when used with newer VM SKUs.

The image you are using, Windows Server 2025 Datacenter: Azure Edition, is Hotpatch-compatible by default. For such images, Azure requires the patch orchestration mode to be explicitly set to AutomaticByPlatform, as Hotpatch depends on Azure-managed patching and does not work with other patch modes. When this setting is not defined or is set differently, the platform blocks the deployment with the validation error you encountered.

This is not a regional issue with West US 2. The difference comes from the VM SKU being used. In your East US and West US deployments, you were using the Standard_DC4as_v5 SKU, which did not strictly enforce the Hotpatch requirement, allowing the deployment to succeed without explicitly setting the patch mode. However, when using the newer Standard_DC4as_v6 SKU in West US 2, the platform enforces stricter validation for Hotpatch-compatible images, requiring the patch mode to be explicitly configured.

To resolve the issue, you need to update your VMSS configuration to explicitly set the patch mode to AutomaticByPlatform. A sample configuration is shown below for reference:

      "windowsConfiguration": {
        "enableAutomaticUpdates": true,
        "patchSettings": {
          "patchMode": "AutomaticByPlatform"
        }
      }
    }
  }
}

If you are using Azure CLI, you can achieve the same by specifying the patch mode under Windows OS patch settings: --patch-mode AutomaticByPlatform

Once this configuration is applied, the VM Scale Set deployment in West US 2 with the Standard_DC4as_v6 SKU should complete successfully.

As an alternative, if Hotpatch is not required for your scenario, you may consider using a non-Hotpatch image or continuing with the Standard_DC4as_v5 SKU where this enforcement is not applied. It is also a good practice to verify SKU availability and compatibility for the target region when planning deployments.

References:

https://learn.microsoft.com/en-us/azure/templates/microsoft.compute/virtualmachinescalesets?pivots=deployment-language-bicep

https://learn.microsoft.com/en-us/azure/virtual-machines/automatic-vm-guest-patching

https://learn.microsoft.com/en-us/windows-server/get-started/hotpatch

Hope this helps! Please let me know if you have any queries.

Thanks for replying Hemalatha,

But I believe Standard_DC4as_v5 SKU is not available in West US 2 region. Only v6 is there. Can you please suggest me a similar confidential VM which is available in West US 2

Hello @Nishtha Agrawal, Just following up to see if you had a chance to look over the response Hemalatha shared earlier. Please let us know if it addressed your question.