Q. PowerShell is not working on my domain controllers with an error related to AD Web Services.
A. The Active Directory PowerShell cmdlets operate against the Active Directory Web Service which is present on all domain controllers. Make sure the AD Web Services service is running (launch services.msc to view). Note that AD Web Services relies on Netlogon so also ensure Netlogon is running (its startup type should be Automatic). You can try restarting Netlogon and then restart AD Web Services to see if this fixes the problem. If the problem still persists check the Eventlog (eventvwr.exe) and under Applications and Services Logs - Active Directory Web Services look for any errors.