Is there a way to troubleshoot an Unknown error when trying to use Set-MsolUserLicense in Powershell?

Question

I have generated this test code to attempt assigning user license assignments to Azure via PowerShell. However, everything functions except the License Assignment. I have debugged every line and narrowed it down to an Unknown error during the communication between PS and the Azure Tennant during the license assignment.

This is the error message I recieve:

Set-MsolUserLicense : Unknown error occurred.

At line:1 char:1

• Set-MsolUserLicense -UserPrincipalName censoredUPN@UPN* ...

• 
      + CategoryInfo          : OperationStopped: (:) [Set-MsolUserLicense], MicrosoftOnlineException 
  
      + FullyQualifiedErrorId : Microsoft.Online.Administration.Automation.OperationNotAllowedException,Microsoft.Online.Administration.Aut   
  
     omation.SetUserLicense
  
  

Code Block:

###Variable Declarations left out for OpSec Purposes*** 

Try{
            Connect-MsolService -Credential $Credentials
            Set-MsolUser -UserPrincipalName $upn -UsageLocation US -ErrorAction Stop
            Write-Output "Trying to Assign License $azureLicense to user $upn, Error Action is to stop" # Debugging Write Statement, can be removed once functionality is restored.
            Set-MsolUserLicense -UserPrincipalName $upn -AddLicenses $azureLicense -ErrorAction Stop
            Write-Output "If this Line prints, code moved past the License set attempt"
            [Microsoft.Online.Administration.Automation.ConnectMsolService]::ClearUserSessionState()
        }
        #If assigning license fails, send failed outcome to Okta
        Catch{
            $headers = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
            $headers.Add("Content-Type", "application/json")
            $body = "{
                    `n    `"outcome`":`"failed-license`",
                    `n    `"upn`":`"$upn`"
                    `n}"
            #$failResponse = Invoke-RestMethod $invokeURL -Method 'POST' -Headers $headers -Body $body
            Write-Host "License Assignment Failed: $_"
            $body
            Write-Output "Script attempted to write back to Okta via the Catch Block for License Failure, If no Logging in Okta, this step failed." #Debugging Write Statement, can be removed later.  
        }

Answer 1

Set-MsolUserLicense is now deprecated mate, you need to switch to using either the Azure AD module, or (recommended) the Graph SDK for PowerShell, both of which leverage the new (and only supported) licensing APIs.

Here's a sample article with detailed steps: https://learn.microsoft.com/en-us/microsoft-365/enterprise/assign-licenses-to-user-accounts-with-microsoft-365-powershell?view=o365-worldwide