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Facing issue with VMSS allocation of virtual machines in East US region.

Dinesh Kumar Gurrala 0 Reputation points
2025-10-28T11:31:31.46+00:00

Hi team,

We are facing issue with VMSS in East US region with allocation of virtual machine when trying to start the VMSS. Due to this issue our Preprod environment is impacted. I tried resize the VMSS with different virtual series but the outcome is same stating allocation of virtual machines are Failed to execute 'start' on the virtual machine scale set '<removed VMSS name>'. Error: Allocation failed. We do not have sufficient capacity for the requested VM size in this zone.

Azure Virtual Machine Scale Sets
Azure Virtual Machine Scale Sets
Azure compute resources that are used to create and manage groups of heterogeneous load-balanced virtual machines.

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  1. Manish Deshpande 1,170 Reputation points Microsoft External Staff Moderator
    2025-10-28T13:01:51.6466667+00:00

    Hello Dinesh,

    Thank you for reaching out to Microsoft Q&A.

    • We understand that your Preprod environment is impacted due to allocation failures when starting or resizing your Virtual Machine Scale Set (VMSS) in the East US region. The error message: Allocation failed We do not have sufficient capacity for the requested VM size in this zone.
    • It indicates that Azure currently does not have enough capacity for the requested VM size in the specified zone.
    • This happens due to -
      • Regional or zonal capacity constraints.
      • Over constrained requirements (specific zone, proximity placement groups, availability sets).
      • Older VM sizes or large deployments.
    • Retry the operation later capacity may become available as resources are freed.
    • Change VM size or series Select a size with better availability in East US or consider newer SKUs.
    • Avoid pinning to a specific zone if possible. Remove proximity placement groups or availability set constraints.
    • Use a different region or zone If East US remains constrained, consider deploying in East US 2 or another region.
    • Scale gradually For large deployments, add VMs in smaller batches.
    • Check Azure Resource Health Verify if there are capacity issues in East US.
    • This is a regional capacity limitation rather than a configuration issue. The quickest resolution is to:
      • Retry later.
      • Switch to a different VM size or region.
    • Reference link - https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/windows/allocation-failure

    Kindly let us know if the above helps or you need further assistance on this issue.

    Thanks,
    Manish Deshpande.

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