New-AzureRmRoleAssignment : Object reference not set to an instance of an object - azure-runbook

Question

Unable to assign role to user using New-AzureRmRoleAssignment command. When I run the above command its thronging an error as follows .
New-AzureRmRoleAssignment : Object reference not set to an instance of an object.
Can any one help to resole the issue.

Answer 1

To assign role to user successfully in the runbook, follow the steps below.
Note : The New-AzureRmRoleAssignment you used belongs to the old AzureRM, it was deprecated and will not be updated anymore. In my sample, I use the new Az command New-AzRoleAssignment, I also recommend you to use it.
1.Navigate to the subscription in the portal(you need to be Owner/User Access Administrator in the subscription) -> add the service principal of your automation RunAs account as an Owner/User Access Administrator(by default it will be added as Contributor when it was created, but Contributor have no permission to run New-AzRoleAssignment).
2.Navigate to the Azure Active Directory in the portal -> App registrations -> find the AD App of your RunAs Account and add the Directory.Read.All application permission in Azure Active Directory Graph(Not Microsoft Graph) like below, don't forget to click the Grant admin consent for xxx button at last(you need to be the admin role in your AAD tenant). The permission may take about 30 min to take effect.
3.Navigate to the automation account in the portal -> Modules -> make sure you have installed the Az.Accounts, Az.Resources modules, if not, go to Browse Gallery, search for the names, and install them.
4.Then in the runbook, use the script below, it works fine on my side. In my sample, I add the user as a Reader in the resource group joyRG, you can change it, it depends on your requirement.
$connectionName = "AzureRunAsConnection"
try
{
# Get the connection "AzureRunAsConnection "
$servicePrincipalConnection=Get-AutomationConnection -Name $connectionName
"Logging in to Azure..."
Connect-AzAccount `
-ServicePrincipal `
-TenantId $servicePrincipalConnection.TenantId `
-ApplicationId $servicePrincipalConnection.ApplicationId `
-CertificateThumbprint $servicePrincipalConnection.CertificateThumbprint
}
catch {
if (!$servicePrincipalConnection)
{
$ErrorMessage = "Connection $connectionName not found."
throw $ErrorMessage
} else{
Write-Error -Message $_.Exception
throw $_.Exception
}
}
$user = Get-AzADUser -UserPrincipalName joyw2#xxxx.onmicrosoft.com
New-AzRoleAssignment -ObjectId $user.id -ResourceGroupName joyRG -RoleDefinitionName Reader