This is how I resolved the error message “Get-MpComputerStatus : The extrinsic Method could not be executed.“, in my specific situation.
In my situation, I had Windows Defender Antivirus disabled per GPO (“Turn off Windows Defender Antivirus” in Computer Configuration/Administrative Templates/Windows Components/Windows Defender Antivirus). And I wanted to enable Windows Defender in a new GPO, on a specific set of computers.
After I specifically enabled Windows Defender on that set computers (OU), by disabling the above referenced GPO setting, I could still not enable Windows Defender, start the services or get its status.
It errored out:
Get-MpComputerStatus : The extrinsic Method could not be executed. At line:1 char:2 + (Get-MpComputerStatus).AMServiceEnabled + ~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : MetadataError: (MSFT_MpComputerStatus:ROOT\Microsoft\...pComputerStatus) [Get-MpComputer Status], CimException + FullyQualifiedErrorId : MI RESULT 16,Get-MpComputerStatus
The fix? Enable Windows Defender using
MpCmdRun.exe located in C:\Program Files\Windows Defender:
C:\Program Files\Windows Defender\MpCmdRun.exe -wdenable