Can't change a Replicating VM Size in Azure Migrate

Question

Can't change a Replicating VM Size in Azure Migrate

Lucas Ruffo 0

I'm replicating some physical servers to Azure using the Azure Migrate. It was fine until I had to change the a size from a VM that still replicating to a more appropriate size.

I'm getting the following error. Looks like something with the Azure Portal.

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Is there any other way to change the VM Size in Azure Migrate?

Thanks!

Bharath Y P 500 Reputation points Microsoft External Staff Moderator

2025-08-26T16:25:37.77+00:00
Hello Lucas Ruffo,

You're replicating physical servers to Azure using Azure Migrate. While replication was working fine, you attempted to change the VM size for one of the machines still undergoing replication. Upon doing so, you encountered errors in the portal.

The Azure Migrate portal extension might fail to load certain configuration panes (like VM sizing, network mapping). Looks like the issue is not your replication

You can follow the below steps to Change VM Size During Replication (using PowerShell):

Login and Set Subscription Context:

Connect-AzAccount Set-AzContext -SubscriptionId "<Your-Subscription-ID>"

Ensure You’re in the Correct Vault Context: Before running the script, make sure you've selected the right vault:

# Get your Recovery Services Vault $vault = Get-AzRecoveryServicesVault -Name "<Your-Vault-Name>" # Set context so that ASR (Azure Site Recovery) commands apply to this vault Set-AzRecoveryServicesVaultContext -Vault $vault

Verify the Fabric and Container Names: These must match exactly what’s configured in your Azure Migrate project. You can list them using:

# List all Fabrics (e.g., VMware, Hyper-V, Azure) Get-AzRecoveryServicesAsrFabric # List containers within a fabric Get-AzRecoveryServicesAsrProtectionContainer -FabricName "<Your-Fabric-Name>"

Check Available VM Sizes in the Target Region:

Get-AzVMSize -Location "<your-region>"

Retrieve the Replication Protected Item (your VM)

# Get the replication protected item $replicatedVM = Get-AzRecoveryServicesAsrReplicationProtectedItem ` -FabricName "Azure" ` -ProtectionContainerName "<your-container>" ` -FriendlyName "<your-VM-name>"

Update the Target VM Size

# Update target size Set-AzRecoveryServicesAsrReplicationProtectedItem ` -InputObject $replicatedVM ` -TargetVmSize "<your new VM size>"

You can follow the above steps to change the VM size during replication using PowerShell, which bypasses the broken Azure Portal interface.

For additional information, you can refer to:

Automate migration of machines in Azure Migrate - Azure Migrate | Microsoft Learn

Hope this helps. Feel free to reach out to us if you have any further questions!

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Answer 1

Hello Lucas Ruffo,

Welcome to the Microsoft Q&A and thank you for posting your questions here.

I understand that you can't change a Replicating VM Size in Azure Migrate.

VM Size cannot be changed during replication, the best practice is that you do not need to re-replicate if you want to change the VM size. Just wait until the migration step and override the size there. Once replication starts, the VM size setting is locked in the Azure Migrate portal.

The options you have are:

You can select the VM size before enabling replication.
During the Test migration or Migrate operation, Azure provisions the VM and allows you to override the VM size. In the migration wizard, you can select a different size before finalizing the deployment.
Once the VM is running in Azure, you can stop it and resize it from the Azure VM blade.

You cannot change the VM size directly during active replication in Azure Migrate. However, a supported method to change the target VM size is by configuring it in the Replicated Items blade of the Recovery Services vault or via ASR PowerShell, during the failover or migration setup phase. This avoids limitations in the Azure Migrate blade and is the recommended route for customizing VM size before migration. https://learn.microsoft.com/en-us/azure/site-recovery/azure-to-azure-how-to-enable-replication and https://learn.microsoft.com/en-us/azure/site-recovery/azure-to-azure-powershell justified this point.

I hope this is helpful! Do not hesitate to let me know if you have any other questions or clarifications.

Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful.

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Can't change a Replicating VM Size in Azure Migrate

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