ADprep Conflict Promoting a Windows 2012 R2 DC Server to a Windows 2008 R2 Domain

It has been quite a while since I last posted anything. So this one was such pain to track down I decided to post it and hopefully it helps somebody save some time and lots of aggravation!

I ran into this prerequisites check error below while promoting a Windows 2012 R2 DC Server to a Windows 2008 R2 Domain

The issue is related to WMI on the existing 2008 R2 DC where the WMI class objects are invalid.

Note: If you run adprep /forest prep from a command line you will also see this error Microsoft WMI Invalid Class Error [0x80041010

Note: I also tried running adprep /forestprep from a command line on the Windows 2008 R2 DC itself and it still failed 
 

After many frustrating hours of researching and trying all types of things I ran across this post which led me in the correct direction https://www.virtuallyboring.com/microsoft-wmi-invalid-class-error-0x80041010/

Note: I run everything from an elevated Windows Command line just in case

Run the Winmgmt.msc and select properties which will display if there are any issues with the WMI classes

 

If the WMI has an invalid class as seen above then download the Microsoft WMIDiag tool https://www.microsoft.com/en-us/download/details.aspx?id=7684

Extract it and Right click on the WMIDiag VBScript and select Open with Command Prompt

The script can run for a while and will eventually produce a text file. The text file will most likely identify a number of issues with .MOF extensions.

To resolve these issues

cd c:\Windows\Syetm32\wbem

An then run this command below:   

dir /b *.mof *.mfl | findstr /v /i uninstall > moflist.txt & for /F %s in (moflist.txt) do mofcomp %s

Run the Winmgmt.msc and select properties which will display if there are any issues with the WMI classes and you should now see something like this below

You can now go back and re-run the DC promotion process on the Windows 2012 R2 server

Continue with the DC promotion process and Reboot when required, etc.