Hi Andreas,
We have identified the issue and it is from this 'small change' in the UR4 upgrade:
https://support.microsoft.com/en-us/topic/update-rollup-4-for-system-center-operations-manager-2019-07ad0ef3-a330-4373-92f6-2dda3821bee5 :
"The MP Reference Alias generator is case-sensitive now and will create only unique Aliases for Management packs."
This means that in the past Alias References were not checked if they were key sensitive so you might have MPs with Alias References such as:
VMware and VMWARE - in the same MP.
You can check with the script bellow, run it on a MS:
$mps = Get-ChildItem -Path "C:\Program Files\Microsoft System Center\Operations Manager\Server\Health Service State\Management Packs"
foreach ($mp in $mps) {
$mpText = Get-Content $mp.PSPath
$references = @()
foreach ($line in $mpText) {
if ($line -like "Reference Alias") {
$references += $line.ToLower()
}
}
$ht = @{}
$references | foreach { $ht["$"] += 1}
$ht.keys | where {$ht["$"] -gt 1} | foreach {write-host "Duplicate element found $_"; write-host $mp.PSPath }
}
If you do have such MPs from custom or 3rd party vendors you will need to remove them, perform the upgrade and reimport them after, or fix the Reference name inside the MP so that they don't repeat, even without being key-sensitive.