Azure error creating a batch pool with spot virtual machines.

I did more testing. The issue is not with capacity in the region or vmsize. It is caused by Pool allocation mode. When I set Pool allocation mode to "Batch service", the batch pool can allocate vms without any issue. But when I set Pool allocation mode to "User subscription", I always get the Resize errors. I also tried using the same vmsize to create a Virtual machine scale set and it works ok. So the vmsize has enough capacity in Australia East region. There's definitely something wrong with "User subscription" mode in batch service.

As stated in the following article, I have to switch to "User subscription" mode to use spot vms because Low-priority VMs will be retired after 30 September 2025.

https://free.blessedness.top/en-us/azure/batch/batch-spot-vms

Hi JunMa,

Thanks for confirming that the issue is not related to size or region and for sharing your findings.

The issue with Azure Batch pool creation failing to allocate Spot VMs when using Pool allocation mode "User subscription" is often related to additional permission and configuration requirements of this mode,

Unlike the "Batch service" mode where the Batch service manages VM allocation, the "User subscription" mode requires the Batch service to directly manage VMs within your subscription.

1. The Batch service must have Contributor or Owner role on your subscription to create and manage VMs.
2. You must accept the legal terms for any marketplace VM images before Batch can allocate VMs using those images.
3. The Batch service principal should be assigned the Azure Batch Service Orchestration Role

If any of these prerequisites are missing or not configured correctly, pool resizing or VM allocation will with errors

Reference: https://free.blessedness.top/en-us/azure/batch/batch-account-create-portal#additional-configuration-for-user-subscription-mode

https://free.blessedness.top/en-us/azure/batch/batch-role-based-access-control

https://free.blessedness.top/en-us/azure/batch/batch-role-based-access-control#azure-batch-built-in-rbac-roles

Could you please check the above steps and provide me the status. This will help me proceed with further troubleshooting.

Hi JunMa,

I wanted to follow up regarding the Azure Batch pool allocation issue. Could you please confirm if the necessary permissions and configurations for the "User subscription" mode have been reviewed and applied. This will help us proceed with the next steps in troubleshooting.

Looking forward to your update.

Hi Jilakara,

I still get the same error message when creating a batch pool with spot/low priority nodes in user subscription mode. The same vmsize and OS works in batch service mode, I was able to get 5 spot/low priority nodes allocated.

Dedicated node works in user subscription mode, I was able to get 5 dedicated nodes allocated with the same vmsize and OS.

I have followed the article and did the following:

Added Azure Batch Service Orchestration Role to Microsoft Azure Batch in Subscription.

Add Key Vault Secrets Officer role to Microsoft Azure Batch in Key vault

Accepted the legal terms using: Set-AzMarketplaceTerms -Publisher "microsoftwindowsserver" -Product "windowsserver" -Name "2025-datacenter-smalldisk-g2" -Accept

Hi JunMa,

I have reproduced the same scenario from my end, and I was able to successfully create a pool in User Subscription mode.

Screenshots:

From the screenshots you shared regarding the access, I noticed that only the Azure Batch Service Orchestration Role was assigned.

Please note that the Orchestration Role helps specifically with managing batch-specific resources, but general VM creation requires the Contributor role at the subscription level.

In my environment, I have the following roles assigned at the subscription level:

• Azure Batch Account Contributor
• Azure Batch Data Contributor
• Azure Batch Service Orchestration Role

Without the Contributor permissions, the Batch service cannot provision VMs in User Subscription mode, which leads to allocation failures as you are experiencing.

I recommend adding Azure Batch Account Contributor and Azure Batch Data Contributor at the subscription level will resolve this issue. Reference: https://free.blessedness.top/en-us/azure/batch/batch-role-based-access-control

Please check and let me know if you have any queries.