PowerShell WMI - The RPC server is unavailable

I have a ongoing task of refining an automated collection (instrumentation) of computers in the organisation running a SQL Server database installation.
Most of the data are collected by WMI and the automation is done by PowerShell.
The other day I ran into a challenge when the computer is available, but the rights are insufficient. The WMI call by the cmdlet Get-WmiObject er initialised as the computer exists, but the data request fails due to the lach of rights. Actually the error does not generate a exception that is caught by the PowerShell try-catch exception handling. It looks like by various fora that it is a remoting issue.

A quick workaround is to take a look at the $Error last element with a match, and filter out the error message with the cmdlet parameter "-ErrorAction SilentlyContinue".
I know that the errormessage contains "HRESULT: 0x800706BA" and a match on this will catch the error in a robust way.


$DebugPreference = 'continue'

$ComputerName = 'SQL30.test.dn.ext'


"{0:s}  `"$ComputerName`"." -f ([System.DateTime]::Now) | Write-Debug




$objComputer = New-Object System.Object

Add-Member -InputObject $objComputer -MemberType NoteProperty -Name Name -Value $ComputerName




$WQL = "SELECT Manufacturer,Model,TotalPhysicalMemory,NumberOfProcessors,SystemType FROM Win32_ComputerSystem"

try {

  $_ComputerSystem = Get-WmiObject -Query $WQL -ComputerName $ComputerName -ErrorAction SilentlyContinue

}

catch [System.UnauthorizedAccessException] {

  ":: ERROR: WMI access denied."

}




# The error "The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)" is not caught but still generates an error

if ($Error[0].Exception -match "HRESULT: 0x800706BA") {

  ":: ERROR: WMI COM (RPC) not available."

}




Add-Member -InputObject $objComputer -MemberType NoteProperty -Name Manufacturer -Value $_ComputerSystem.Manufacturer

Add-Member -InputObject $objComputer -MemberType NoteProperty -Name Model -Value $_ComputerSystem.Model

Add-Member -InputObject $objComputer -MemberType NoteProperty -Name MemoryInKb -Value $(if($hasWmiAccess) {($_wmi.TotalPhysicalMemory / 1KB)} else {$null})

Add-Member -InputObject $objComputer -MemberType NoteProperty -Name CpuCoreCount -Value $_ComputerSystem.NumberOfProcessors

Add-Member -InputObject $objComputer -MemberType NoteProperty -Name SystemType -Value $_ComputerSystem.SystemType




$objComputer