Virtual Machine Deployment Issue: Cannot Select VM Size or Region — Size Not Available

Question

Problem description

I am unable to deploy a Windows-based Virtual Machine in Azure, specifically for a FortiAuthenticator workload. The Azure portal does not allow me to select any VM size, showing errors such as 'size not available,' 'SKU not available,' or indicating that certain sizes are deprecated or unsupported in the chosen region or zone.

Environment

Azure Virtual Machine running Windows, deployment for FortiAuthenticator in Canada Central region, involving availability set or zone, with desired size B2s.

What I've already tried

I attempted to remove the zone requirement and checked the availability of all sizes, but encountered errors for every model, including size, quota, and end-of-life messages. I verified that my usage in Canada Central is under 10% and that quotas are not reached. I also tried different zone settings and checked the marketplace listing for supported sizes and regions.

Current status

I am seeking guidance to identify whether the issue is related to region or zone restrictions, image compatibility, or subscription limitations. I would like assistance in troubleshooting the root cause and finding a way to successfully deploy the VM with the desired specifications.

Answer 1

@ITGuy-1132 Welcome to Microsoft Q&A

This post made by TP might help you https://learn.microsoft.com/en-us/answers/questions/5987951/quota-increase?page=1#answer-12938336

The fact that quota usage is below 10% does not necessarily indicate that the VM size is deployable. Azure evaluates quota, SKU restrictions, regional/zone availability, and capacity separately. A VM can have sufficient quota and still return SkuNotAvailable or NotAvailableForSubscription.

Since you are deploying in Canada Central and have already tested different zones, I recommend checking the SKU directly from the subscription rather than relying only on the portal:

az vm list-skus \

  --location canadacentral \

  --size Standard_B2s \

  --all \

  --output table

Also check the available SKUs for zonal deployment:

az vm list-skus \

  --location canadacentral \

  --zone \

  --all \

  --output table

Look specifically at the Restrictions column. For example:

• NotAvailableForSubscription → the SKU is restricted for this subscription.
• type: Zone → the SKU may be available regionally but restricted in the selected zone.
• None → there is no subscription restriction reported for that SKU.

Microsoft specifically recommends az vm list-skus --all because it exposes SKUs that are unavailable to the current subscription and their restrictions.

If Standard_B2s shows no subscription restriction but deployment still fails, check whether the failure is specifically related to capacity. Azure capacity is independent of quota, so having available quota does not guarantee capacity for a particular VM size in a region or zone.

Because FortiAuthenticator is a virtual appliance, I would also verify the Fortinet-supported Azure VM sizes and deployment requirements before switching to another SKU. The replacement should be both Azure-available and supported by Fortinet.

References:

https://learn.microsoft.com/en-us/azure/azure-resource-manager/troubleshooting/error-sku-not-available

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

https://learn.microsoft.com/en-us/cli/azure/vm#az-vm-list-skus

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