If you’ve deployed a Windows Server 2008 core install running AD DS, you’ll be familiar with the promotion process. If you’ve ever demoted a Domain Controller from the command line, you may have come across an issue which makes your heart skip a beat (the last thing you want is for a Domain Controller promotion or demotion operation to fail, because you never know what you’re going to be left with). It’s actually a pretty easy “fix” which is handy to know before you try going crazy in adsiedit or anything like that.
The error can occur while the demotion process is attempting to stop the NETLOGON service, however the stop request times out, you get a message indicating that the operation has completed, but then an error on the next immediate line and your demotion stops.
Stopping service NETLOGON
The attempted domain controller operation has completed
Failed to configure the service NETLOGON as requested
When I first did this, I figured that the dcpromo process would be aware of the last failure, and retry, which is sort of the case except you get the following error
The wizard cannot access the list of domains in the forest. The error is: the interface is unknown.
Another error which sounds particularly ominous, but it’s not. During the first demotion attempt, the demotion failed because either the NETLOGON service didn’t stop in time, or didn’t return the success code to the stop request, however by the time you run the second demotion the service has stopped. The demotion isn’t going to work with the NETLOGON service stopped.
The solution is as simple as just starting the NETLOGON service again by typing “net start netlogon” from the command, and then retrying your demotion. The dcpromo will pick up from where it was before, and nearly always complete successfully this time around.