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VM Generation Mismatch- Not Booting

Sijin N P 0 Reputation points
2025-11-06T12:58:05.8533333+00:00

Hi Team,

I’ve created the VM as Generation 2 in the on-premises environment and replicated to Azure SR and replication is successful, but during the Test Failover in Azure, it started as a Generation 1 VM and we are not able to connect the RDP and as per our research we found that, VM is not booting due to this mismatch.

However, I’m still unsure how to change or configure the VM to Generation 2 in Azure. If anyone has experience with this or knows the correct approach, your input would be greatly appreciated.

Azure Site Recovery
Azure Site Recovery
An Azure native disaster recovery service. Previously known as Microsoft Azure Hyper-V Recovery Manager.

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  1. Bharath Y P 2,560 Reputation points Microsoft External Staff Moderator
    2025-11-06T14:30:11.9766667+00:00

    Hello Sijin N P,

    It looks like you're facing an issue with your Azure VM booting as Generation 1 instead of Generation 2, which can indeed mess with your ability to connect via RDP. This kind of mismatch often arises during the replication process with Azure Site Recovery (ASR).

    You want to ensure the VM was properly configured as Generation 2 before the replication. Unfortunately, Azure doesn't provide a straightforward way to convert a Generation 1 VM to Generation 2, especially once the VM has been created.

    Confirm Source VM Is Generation: On your on-premises Hyper-V or VMware host, verify the VM is configured as Generation 2.

    • Go to Azure portal > In the Recovery Services Vault,
    • Navigate to Replicated Items and check the Target VM Generation under Compute and Network.
    • Ensure that ASR is set to replicate Generation 2 VMs properly,

    If it shows Generation 1, this mismatch will cause boot issues during failover. re-trigger the replication process to ensure it reflects the correct generation.

    Update Target VM Generation: In the Compute and Network section > Click Edit > Change the Target VM Generation to Generation 2 > Save the changes.

    If the option is unavailable, you may need to disable replication, clean up the failed-over VM, and re-enable replication from scratch with the correct generation setting.

    Recreate the VM Using ASR (Generate a New VM in Azure):

    You do manual cleanup of incorrect VM:

    • Go to the Recovery Services Vault in Azure.
    • Locate the Replicated Item for the affected VM.
    • If a Test Failover VM was created as Generation 1:
      • Stop and delete the failed-over VM.
      • Detach the OS disk if needed for reuse.

    Disable and Re-enable Replication:

    • In the Recovery Services Vault:
      • Disable replication for the VM.
      • Confirm cleanup of associated resources (replicated disks, configuration).
    • Re-enable replication:
      • During setup, ensure the Target VM Generation is explicitly set to Generation 2 under Compute and Network settings.

    After making the necessary changes, conduct a test failover again to see if the VM boots correctly as a Generation 2 instance. Monitor the process in the Azure portal for any error messages.

    Reference document:

    Cannot connect with RDP to a Windows VM in Azure - Virtual Machines | Microsoft Learn

    Azure boot diagnostics - Azure Virtual Machines | Microsoft Learn

    If you're still having trouble, here are a few follow-up questions that could help narrow down the cause:

    1. Is there any errors or alerts during the replication setup in ASR?
    2. Have you checked the Boot diagnostics for any specific error messages during the boot process after the failover?
    3. Is the version of the Azure Site Recovery tools and agents up to date?

    I hope this helps, If you encounter any issue, please let us know, Thanks

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