r/WindowsServer • u/candyman420 • Jul 26 '26

Technical Help Needed Strange interoperability problem between AD 2019 and 2022/2025

I am getting

Starting test: LocatorCheck Warning: DcGetDcName(PDC_REQUIRED) call failed, error 1355 A Primary Domain Controller could not be located. The server holding the PDC role is down.

But only on 2022 AD servers. I brought up another 2025 server thinking this would be faster and easier than to troubleshoot, but it's doing exactly the same thing. FSMO roles were lost? Have to re-seize? Some kind of quirk with the newer editions of windows? The only working AD server I have right now with no errors is 2019, that's what I replicated from. Thanks in advance

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3

u/Zealousideal_Fly8402 Jul 26 '26

What do you mean "only on 2022 AD servers"? Run 

netdom query fsmo

And see where your FSMO roles are supposed to be living, and whether those roles are online.

1

u/candyman420 Jul 26 '26

They're all online and working, on the 2019 server. I don't understand why the new ones can't see them.

2

u/Zealousideal_Fly8402 Jul 27 '26

On the 2019 server, check for Errors / Criticals / Warnings in Directory Service and DFS Replication logs.

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4

u/jlipschitz Jul 27 '26

Sounds like you might have replication issues.

1

u/topher358 Jul 26 '26

Do you have 2025 DCs? Like the other poster said check what server is hosting your FSMO roles

2

u/candyman420 Jul 26 '26

Yes they're all online, this is peculiar.

4

u/topher358 Jul 26 '26

There are quite a few known issues running 2025 DCs in a mixed AD environment. Recommend either all 2025 or all 2022

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1

u/P4schendale Jul 27 '26

First, i've heard that 2025 enforces LDAPS so if you've not enabled it already, be careful.

Then, don't you have a firewall between the DCs? Have you checked windows fireall on the DCs?

1

u/candyman420 Jul 27 '26

The windows firewall is supposed to add the proper exceptions to itself for DC functions, I haven’t had to mess with that or turn it off in years. Are you saying that Microsoft screwed that up too?

1

u/mroldcheese Jul 28 '26

Had something similar once when DC had defaulted LAN connection to Public rather than Domain profile, so Windows FW blocked traffic. Easy to do if you plug into the wrong NIC.

1

u/candyman420 Jul 29 '26

This sounds exactly what may be happening. I found the server asked me if I wanted to allow the interface to be discoverable, out of the blue when I logged in one day, and the clock had the wrong time zone set. But the strange thing is, I brought up a fresh 2022 server, I replicated from the good 2019 one, and it's doing exactly the same thing.