Getting this error while updating any resource in VM Scale Set "Error: An unexpected error occured while processing the network profile of the VM. Please retry later."

oh wow, that's a frustrating error to run into )) thanks for posting it here. lets see what we can do to get your vm scale set back on track.

this kind of error often points to a temporary glitch in the azure fabric or a deeper issue with the network profile itself. first thing u should try is simply waiting a bit. sometimes azure is doing background maintenance and just needs 30-60 minutes to finish. go grab a coffee and try again later.

if that doesn't help, the next step is to check the resource health for your vm scale set and the virtual network its using. head to the azure portal, find your scale set, and look for the 'resource health' blade. it might show u if there's a known platform issue going on.

since u can't restart the instances directly, u might need to work around them. try updating the scale set model to a new sku or image version. even a small change can sometimes force the platform to reevaluate the entire set and clear the stuck state. u can do this via the portal or with az cli.

az vmss update --resource-group yourRG --name yourVMSS --set virtualMachineProfile.storageProfile.imageReference.version='latest'

this might help in other tools too, forcing a model update often resolves provisioning glitches.

another thing worth looking into is the network security group attached to your scale set's vnet. if there was a recent change that misconfigured rules, it could block the management plane from communicating with your instances. check the nsg rules for any denies on ports 443 or 44300.

aha, and here's a deeper dive. the error might be related to a specific faulty instance. u can try to delete the failed instances directly. since its a scale set, new ones should be created to replace them. u can do this from the instances blade in the portal. just pick the worst offender and hit delete.

if all else fails, u might need to consider recreating the scale set. i know, its a nuclear option, but if its completely stuck, it might be the fastest path forward. make sure u have your template and config backed up first.

as well check this microsoft doc on troubleshooting vmss update errors https://free.blessedness.top/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-troubleshoot

also, take a peek at your activity logs. filter on your scale set name and look for failed operations around the time this started. the error details there might give u a more specific clue.

hope one of these ideas gets your scale set moving again. let me know how it goes.

Best regards,

Alex

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P.S. If my answer help to you, please Accept my answer

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Hi Sarma Vutukuri,

The error that you are facing "An unexpected error occurred while processing the network profile of the VM. Please retry later" indicates that the network profile of your scale set is in an inconsistent state. It often happens when:

• A subnet, Load Balancer, or Network Security Group (NSG) that the VMSS depends on was deleted or modified.
• The VMSS model is still referencing backend pools or IP configurations that no longer exist.
• One or more VM instances are stuck in a Failed state due to these invalid references.

Due to this, operations like restart, reimage, stop/start, or resize will all fail since they interact with the NICs. To troubleshoot the issue, follow the steps below:

1.Check activity logs to view the recent failures for your VMSS using the Bash command below to identify which resource (subnet, LB, NSG) is missing or invalid:

az monitor activity-log list --resource-id <VMSS-RESOURCE-ID> --status Failed --max-events 5

2.Inspect the VMSS network profile and review the output for invalid or missing references.

az vmss show -g <RESOURCE-GROUP> -n <VMSS-NAME> --query "virtualMachineProfile.networkProfile"

This step can help us identify to whether we need to fix the model or just clean up failed instances to get the VMSS back to a healthy state.

3.Update the VMSS model to fix/remove invalid references like removing a broken load balancer backend pool reference (eliminate unnecessary references)

az vmss update

-g <RESOURCE-GROUP>

-n <VMSS-NAME>

--remove virtualMachineProfile.networkProfile.networkInterfaceConfigurations[0].ipConfigurations[0].loadBalancerBackendAddressPools

4. If only some instances are affected, you can delete and replace them.

az vmss delete-instances -g <RESOURCE-GROUP> -n <VMSS-NAME> --instance-ids <INSTANCE-ID>

The scale set will create healthy replacements.

5.If the entire VMSS is corrupted, backup the data disks. And redeploy the VMSS with a valid network configuration.

For more information, refer here: VM restarting or resizing issues in Azure - Virtual Machines | Microsoft Learn

Failed to start virtual machine - Microsoft Q&A

Virtual machine stuck in failed state - Virtual Machines | Microsoft Learn

Modify an Azure Virtual Machine Scale Set - Azure Virtual Machine Scale Sets | Microsoft Learn

az vmss | Microsoft Learn

Kindly check the above steps and references provided to troubleshoot your issue. Let me know if you require any additional assistance from my end. I am happy to help you with the queries. If the information is helpful, please click on Upvote and Accept Answer on it so that it can help other community members.

Thanks,

Rashmika