How-to fix Windows Defender error "Get-MpComputerStatus : The extrinsic Method could not be executed."

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.

Mehh... 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

Windows Defender: Turn off routine remediation

The fix? Enable Windows Defender using MpCmdRun.exe located in C:\Program Files\Windows Defender:

C:\Program Files\Windows Defender\MpCmdRun.exe -wdenable

And reboot.