Unable to create VM in Azure Devtest Lab

Question

Unable to create VM in Azure Devtest Lab

DevOpps 25

Hi,

I have a free tier Azure devtest lab account with $200 credits added. I am trying to create a VM with using the Linux base with default available DC series and Standard_DC2as_v5 available VM size, still I keep getting error on VM creation. I tried selecting different base images and sizes but always keep getting error. Below is the latest error

"statusMessage": "{"status":"Failed","error":{"code":"ResourceOperationFailure","message":"The resource operation completed with terminal provisioning state 'Failed'.","details":[{"code":"BadRequest","message":"The VM size 'Standard_DC2as_v5' is not supported for creation of VMs and Virtual Machine Scale Set with '<NULL>' security type."}]}}

Help me resolve this at the earliest, as this is blocking the progress.

Answer accepted by question author

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Answer 1

Jilakara Hemalatha 6,050 Microsoft External Staff Moderator

Hello @DevOpps

The error you're encountering when trying to create a VM in Azure DevTest Labs with the Standard_DC2as_v5 size is due to a mismatch between the VM size and the security type configuration. The specific error message:

"The VM size 'Standard_DC2as_v5' is not supported for creation of VMs and Virtual Machine Scale Set with '<NULL>' security type."

User's image

Here you need to select the security type as Trusted Launch. For Standard_DC2as_v5 size if you select the security type to Trusted launch VM creation will fail with below error.

The VM size 'Standard_DC2as_v5' is not supported for creation of VMs and Virtual Machine Scale Sets with 'TrustedLaunch' security type.

This is because DCas_v5 sizes are not compatible with either <NULL> or Trusted Launch. They only work when deployed as Confidential VMs, which DevTest Labs does not support.

Confidential VMs support the following VM sizes:

General Purpose without local disk: DCasv5-series, DCesv5-series
General Purpose with local disk: DCadsv5-series, DCedsv5-series
Memory Optimized without local disk: ECasv5-series, ECesv5-series
Memory Optimized with local disk: ECadsv5-series, ECedsv5-series
NVIDIA H100 Tensor Core GPU powered NCCadsH100v5-series

Reference: About Azure confidential VMs

Azure DevTest Labs does not support Confidential VM SKUs. Therefore, we recommend selecting a non-confidential (standard) VM size when creating VMs inside DevTest Labs.

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

DevOpps 25 Reputation points

2025-11-25T06:52:11.3766667+00:00

Hi @Jilakara Hemalatha ,

Thanks for your response, I was looking for B series VM sizes, which are cost effective for dev/test environments, but those are not available so had to go for DC series. Can you also help me with correct VM sizes basic level VMs that can be created in DevTest labs.
DevOpps 25 Reputation points

2025-11-25T07:21:29.33+00:00

@Jilakara Hemalatha ,

As suggested, I am checking for given general purpose confidential VM sizes, but those are not available in the list when I am selecting VM size. Please find below screenshot. So you identified my problem correctly, but I am still stuck with relevant VM size selection.
Jilakara Hemalatha 6,050 Reputation points Microsoft External Staff Moderator

2025-11-25T10:52:48.82+00:00

Hello @DevOpps

Thank you for your patience. As you are using a Free Trial account, it is quite possible that B-series SKUs (which are typically the most cost-effective for dev/test workloads) are not enabled for your subscription with DevTest Labs. Because of this, those sizes may not be visible in your VM size list.

Could you please check and confirm — apart from the DC-series, which other VM series or sizes do you see available in your lab’s size-selection list.

Below is the screenshot from my dev/test environment subscription

Go to Configuration & Policies → Allowed Virtual Machine Sizes in the Azure DevTest Lab settings, and check which sizes are permitted in your lab.

Understanding which series are allowed will help us recommend a compatible, cost-effective VM size that works within your current setup.

Please find below documentation for reference

https://learn.microsoft.com/en-us/azure/devtest-labs/devtest-lab-set-lab-policy

Hope this helps! Please let me know if you have any queries.
DevOpps 25 Reputation points

2025-11-25T13:00:59.34+00:00

Hi @Jilakara Hemalatha

All sizes are allowed in the configuration and policies of the devtest lab. Please see below screenshot.

Other than DC series, following series are available in VM Sizes
Jilakara Hemalatha 6,050 Reputation points Microsoft External Staff Moderator

2025-11-25T14:47:53.13+00:00
Click on the selected size and check the sizes you want to deploy.

Check the quota details; if the quota is small, to increase it you need to raise a quota request.

Also, you can see here that the quota is only 4. If it is not sufficient, you need to increase the quota. You can click and raise the request from the top.

Reference doc: https://learn.microsoft.com/en-us/azure/quotas/quickstart-increase-quota-portal

This behavior is expected on Free Trial subscriptions. Below are the reasons:

Subscription quota limits – Free Trial subscriptions have limited VM sizes and cores available. Even if all B-series sizes are selected in policies, the portal will only show the sizes that are allowed for your subscription.

Region availability – Not all B-series sizes may be available in the region you selected.

Policy and image compatibility – Some VM images or security policies may restrict certain sizes.

Upgrading your subscription to Pay-As-You-Go will expand the available VM sizes, allowing you to see and deploy B-series sizes and also raise a quota request.
DevOpps 25 Reputation points

2025-11-25T14:57:23.6033333+00:00

Thanks for your support!!

Answer 2

The error message you are encountering indicates that the VM size 'Standard_DC2as_v5' is not supported for the creation of VMs with the specified security type. Here are a few steps you can take to resolve this issue:

Check VM Size Availability: Ensure that the VM size you are trying to use is available in the region where your Azure DevTest Lab is located. You can verify the availability of VM sizes in your region on the Azure portal or through the Azure documentation.
Change Security Type: If the security type is set to '<NULL>', you may want to specify a valid security type for the VM. This could involve selecting a different VM size that supports the required security type or adjusting the configuration settings in your DevTest Lab.
Use Different Base Images: Since you mentioned trying different base images, ensure that the images you are selecting are compatible with the VM size and security type you are using.
Review Quotas and Limits: Since you are using a free tier account, check if you have reached any quotas or limits for the resources you can create in Azure DevTest Labs.
Consult Activity Logs: Look at the activity logs for your lab to find more detailed error messages that could provide further insight into the failure. This can help identify if there are other underlying issues affecting the VM creation.

If these steps do not resolve the issue, consider reaching out to Azure support for further assistance.

References:

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Unable to create VM in Azure Devtest Lab

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