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Matt Walker
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Unable to join a new domain controller to the domain. Forest version issues.

We are currently working on moving from Windows 2012 R2 as the DC to Windows 2019.  We're running both of these machines on VMware ESXi 7.  When I try to add the 2019 server as a domain controller, I receive the error message:

"Verification of replica failed. The forest functional level is not supported. To install a Windows Server 2019 domain or domain controller, the forest functional level must be Windows Server 2008 or higher."

I then ran Get-ADForest on the 2012 domain controller, and the output for ForestMode is "Windows2003Forest."  So, I popped the Windows 2012 R2 iso into the virtual drive to run ADprep /forestprep, but I get a message that says Forest-wide information has already been updated, and it didn't attempt to rerun.

So, I'm at a loss at this point.  Is there a way to force forestprep to rerun?

Windows OSWindows Server 2012VMware

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8/22/2022 - Mon
Daryl Ponting

If you have a Windows Server 2012 R2 Domain Controller, then the forest prep and domain prep have already been done for 2012 R2.

If you have no Windows Server 2003 domain controllers, you can raise the domain and forest functional levels.

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