Azure Automation Account - Runbook Error - Object reference not set to an instance of an object - azure

Question

Last week, I deployed a script to backup some disks using the New-AzSnapshot cmdlet.
I scheduled this script in the Azure Automation Account and for the first 2 days, the script worked very well!
Today, I analyzed the logs and saw that the script had the error below:
Connect-AzAccount : Object reference not set to an instance of an object. At line:12 char:25 + $connectionResult = Connect-AzAccount ` + ~~~~~~~~~~~~~~~~~~~ + CategoryInfo : CloseError: (:) [Connect-AzAccount], NullReferenceException + FullyQualifiedErrorId : Microsoft.Azure.Commands.Profile.ConnectAzureRmAccountCommand
Does anyone have any idea what may be causing this error?
Below the script:
Param(
[string]$resourceGroupName
)
$connection = Get-AutomationConnection -Name AzureRunAsConnection
while (!($connectionResult) -And ($logonAttempt -le 10)) {
$LogonAttempt++
# Logging in to Azure...
$connectionResult = Connect-AzAccount `
-ServicePrincipal `
-Tenant $connection.TenantID `
-ApplicationID $connection.ApplicationID `
-CertificateThumbprint $connection.CertificateThumbprint
Start-Sleep -Seconds 30
}
# Remove old snapshots
$snapshotnames = (Get-AzSnapshot -ResourceGroupName $resourceGroupName).name
foreach($snapname in $snapshotnames)
{
Get-AzSnapshot -ResourceGroupName $resourceGroupName -SnapshotName $snapname | ?{($_.TimeCreated) -lt ([datetime]::UtcNow.AddMinutes(-10080))} | Remove-AzSnapshot -Force
}
foreach ($VMs in Get-AzVM -ResourceGroupName $resourceGroupName) {
#Set local variables
$location = $VMs.Location
#$resourceGroupName = $vmInfo.ResourceGroupName
$timestamp = Get-Date -f MM-dd-yyyy_HH_mm_ss
#Snapshot name of OS data disk
$snapshotName = "bkp-" + $VMs.Name + "-" + $timestamp
#Create snapshot configuration
$snapshot = New-AzSnapshotConfig -SourceUri $VMs.StorageProfile.OsDisk.ManagedDisk.Id -Location $location -CreateOption copy
#Take snapshot
New-AzSnapshot -Snapshot $snapshot -SnapshotName $snapshotName -ResourceGroupName $resourceGroupName
if ($VMs.StorageProfile.DataDisks.Count -ge 1) {
#Condition with more than one data disks
for ($i = 0; $i -le $VMs.StorageProfile.DataDisks.Count - 1; $i++) {
#Snapshot name of OS data disk
$snapshotName = "bkp-" + $VMs.StorageProfile.DataDisks[$i].Name + "-" + $timestamp
#Create snapshot configuration
$snapshot = New-AzSnapshotConfig -SourceUri $VMs.StorageProfile.DataDisks[$i].ManagedDisk.Id -Location $location -CreateOption copy
#Take snapshot
New-AzSnapshot -Snapshot $snapshot -SnapshotName $snapshotName -ResourceGroupName $resourceGroupName
}
}
else {
Write-Host $VMs.Name + " doesn't have any additional data disk."
}
}

Answer 1

You're having a nullreference exception, looking at the location inside the error message (At line:12 char:25). it shows that connection is null.
You need to declare connection first on the same page before you're able to use the variables inside.
See also: What is a NullReferenceException, and how do I fix it?
EDIT: At second notice, I think that you're already declaring the $connection at
$connection = Get-AutomationConnection -Name AzureRunAsConnection
but it looks like that's returning null. In that case, you'll need to figure out why that's returning null, because it should return a filled $connection if connected.
For a safe check to avoid errors: you should check first if the $connection is not null before entering the while, (for example $connection != null could work for Javascript). That way you won't get errors, but keep in mind that you won't get a result through this.