Having trouble demoting one of my servers. This domain originally had 2 Server 2003 DC's. Last weekend I successfully demoted one with relatively no issues. I brought up 2 new Server 2012r2 DC's across 2 sites to replace these. I'm on this last one and when I run dcpromo I get to the last page where it actually tries to demote the server and immediately get an "The operation failed, invalid handle" error. The first time it ran for a few minutes, but on subsequent times it immediately fails.
I inherited this domain and I know this server used to run Exchange 2003. All mailboxes and public folders have been moved to a new Exchange 2010 Server. All Exchange services are disabled on this machine. It was uninstalled, albeit with some issues, and the system manager is still on there. However, it doesn't handle any mail functions.
The error in dcpromo.log.
04/26 21:34:08 [ERROR] Failed to load NTDSETUP.DLL
04/26 21:34:08 [ERROR] Internal error trying to initialize operation handle (126).
04/26 21:34:08 [INFO] Request for demotion of domain controller
04/26 21:34:08 [INFO] DnsDomainName (NULL)
04/26 21:34:08 [INFO] ServerRole 1
04/26 21:34:08 [INFO] Account (NULL) Options 128
04/26 21:34:08 [INFO] LastDcInDomain FALSE
04/26 21:34:08 [INFO] Forced Demote FALSE
04/26 21:34:08 [INFO] Start the worker task
04/26 21:34:08 [ERROR] Thread 2011571319 unsuccessfully started: 6
04/26 21:34:08 [INFO] Request for demotion returning 6
Also note that I didn't put the null in for domain name or account. Not sure if that intended or it can't be read?
It passes all dcdiag tests when running in verbose mode. It is replicating and performing all functions properly as far as I can tell. Since it immediately happens it seems like an issue with the local system and not AD related.
Any help would be great.