Promotion of server 2019 to DC in 2012r2 failed. 2012r2 fuctional level does not support 2019.

Question

I have a single 2012r2 server domain controller functioning properly at the 2012r2 forest/domain functional level.
I added a single 2019 server to the domain, installed AD services, and attempted to promote to a domain controller.
Here is the error:

"To update the domain functional level, the Active Directory Domain Controllers in the domain must be running the appropriate version of windows.

domain Name
domain.local

Current domain functional level
Windows Server 2012 R2

The following Active Directory Domain Controllers are running earlier versions of windows:
domain Name AD DC Version of Windows
domain.local SERVER001.domain.local Windows Server 2012 R2 Standard 6.3 (9600)"

I have verified that the forest/domain is at 2012r2 and everything I have read on this topic tells me that server 2019's minimum functional level to be a DC is 2008.

What forest/domain level do I need to be at before I can add a 2019 DC?
If your answer is 2012r2 or lower, why doesn't it work?

Thanks in advance!

Answer 1

The two prerequisites to introducing the first 2019 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYSVOL/ba-p/425405

Please run;

Dcdiag /v /c /d /e /s:%computername% >C:\dcdiag.log
repadmin /showrepl >C:\repl.txt
ipconfig /all > C:\dc1.txt
ipconfig /all > C:\dc2.txt

then put unzipped text files up on OneDrive and share a link.