Cannot remove or add a server as DC

Question

Hello,
I repaired the AD because a DC was not working right.
We deleted this server an Sites & Services for AD and then the AD worked again.
Now we want to add again this server to the AD and upgrade the server from 2012 to 2019.
But we cannot upgrade that server because the AD forest is not upgraded.
I executed that commands and the output is:
E:\support\adprep>adprep.exe /forestprep

ADPREP WARNING:

Before running adprep, all Windows Active Directory Domain Controllers in the fo
rest must run Windows Server 2003 or later.

You are about to upgrade the schema for the Active Directory forest named 'sam.t
ufast.de', using the Active Directory domain controller (schema master) 'PDM.company.de'.
This operation cannot be reversed after it completes.

[User Action]
If all domain controllers in the forest run Windows Server 2003 or later and you
want to upgrade the schema, confirm by typing 'C' and then press ENTER to conti
nue. Otherwise, type any other key and press ENTER to quit.

C

Forest-wide information has already been updated.
[Status/Consequence]
Adprep did not attempt to rerun this operation.

E:\support\adprep>adprep.exe /domainprep
Domain-wide information has already been updated.
[Status/Consequence]
Adprep did not attempt to rerun this operation.

But in the setup file the line with AD forest don't disappear.

So now we had the idea to add it to the AD again and try the upgrade again:
but here we have the error:
"Error determining the target server is already a domain controller: The domain controller promotion completed, but the server is not advertising as a domain controller."

Then demote the dc from the ad finally:
"DFS Replication Access is denied"

And we cannot deinstall the AD DS because it is still a dc.

So I don't find really a thread or forum, there they had that problem.

Maybe someone can help us?

See you
Jonas

Answer 1

Please run;

Dcdiag /v /c /d /e /s:%computername% >C:\dcdiag.log (run on PDC emulator)
repadmin /showrepl >C:\repl.txt (run on any domain controller)
ipconfig /all > C:\dc1.txt (run on domain controller 1)
ipconfig /all > C:\dc2.txt (run on domain controller 2 if exists)
ipconfig /all > C:\dc3.txt (run on domain controller 3 if exists)

Also check the domain controller System and Replication (DFS or FRS) event logs for errors since last boot. Post the Event Source and Event IDs of any found. (no evtx files)

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

Answer 2

• On TEST-PDM-2022 remove the public DNS (8.8.8.8) then do ipconfig /flushdns, ipconfig /registerdns, then restart the netlogon service.
• PDM-CONTACT-WIN is multi-homed, remove all but a single adapter then do ipconfig /flushdns, ipconfig /registerdns, then restart the netlogon service. Also remove the public DNS (8.8.8.8)
• Looks like there are four domain controllers but ipconfig files only for three. Domain controllers must have their own static address plus loopback (127.0.0.1) listed for DNS and no others such as router or public DNS. I didn't look too much at dcdiag since the above issues are showstoppers. After corrections if problems persist then put up a new set of files to look at.

--please don't forget to upvote and Accept as answer if the reply is helpful--

Answer 3

In short, my co worker solved the problem. He edited things in the registry. I don't know which one.
But thanks for the help :)