Update-AzureRmVmss : Required parameter 'adminPassword' is missing (null) - powershell

Question

I am trying to run a PowerShell vmss custom extension script on scale set.
I get this error when it tries to run the Update-AzureRmVmss command
Update-AzureRmVmss : Required parameter 'adminPassword' is missing (null).
ErrorCode: InvalidParameter
ErrorMessage: Required parameter 'adminPassword' is missing (null).
StatusCode: 400
ReasonPhrase: Bad Request
$customConfig = #{
"fileUris" = #("https://$storageAccountName.blob.core.windows.net/scripts/script.ps1");
"commandToExecute" = "PowerShell -ExecutionPolicy Unrestricted .\script.ps1";
};
# Add the extension to the config
$vmss = Get-AzureRmVmss -ResourceGroupName $resourceGroup -VMScaleSetName $vmssname
Add-AzureRmVmssExtension -VirtualMachineScaleSet $vmss -Publisher Microsoft.Compute -Type CustomScriptExtension -TypeHandlerVersion 2.0 -Name "runscript" -Setting $customConfig
# Send the new config to Azure
Update-AzureRmVmss -ResourceGroupName $resourceGroup -Name "runscript" -VirtualMachineScaleSet $vmss

Answer 1

I figured out the issue.
The -Name needs to be scaleset name. The code I got from online had the name as the name of the script which was wrong.
Update-AzureRmVmss -ResourceGroupName $resourceGroup -Name "scalsetname" -VirtualMachineScaleSet $vmss

Answer 2

It might be easier to use the PowerShell cmdlet or CLI commands to add an extension directly..
PowerShell: Add-AzureRmVmssExtension
CLI: az vmss extension set
The Azure Cloud Shell has a built in authenticated version of CLI.

Answer 3

The correct parameter for Update-AzureRmVmss is -VMScaleSetName which also has an alias called Name.
I was also getting the same error using -Name parameter,
but when I tried using -VMScaleSetName in place of -Name, I do not see the error.
Here is the official documentation for reference: https://learn.microsoft.com/en-us/powershell/module/azurerm.compute/update-azurermvmss?view=azurermps-6.9.0
Update-AzureRmVmss -ResourceGroupName $resourceGroup -VMScaleSetName "scalesetname" -VirtualMachineScaleSet $vmss

Answer 4

If found this thread by searching for Required parameter 'adminPassword' is missing (null), but my solution was a different one.
Turns out that you get this message also if your chosen password does not match the security requirements of the VM (or whatever) you are installing. It is a confusing way to express that issue, to say the least, so maybe this helps someone.