Cannot promote a new Server 2012 R2 server to domain controller on an existing domain. The prerequisites check fails.

Verification of prerequisites for Active Directory preparation failed. 
Unable to verify whether schema master has completed a replication cycle after last reboot.
Exception: Unavailable Critical Extension. Server extended error: 8366.
Server extended message: 000020AE: SvcErr: DSID-03210384, problem 5010
Adprep failed to verify whether schema master has completed a replication
cycle after last reboot.
The schema is not upgraded.
[User Action]
Check the log file ADPrep.log in the
C:\Windows\debug\adprep\logs\20160222090334-test directory for possible cause of failure.

AD Domain Services Prerequisites Check failure

Current domain has a Server 2008 R2 domain controller, with Domain Functional Level set to Server 2008 R2.

When trying to retrieve the Forest Functional Level the error "A referral was returned from the server" is encountered.

A referral was returned from the server

  • 1
    How many DCs are present in sites and services? Are there any failed ones still there
    – Drifter104
    Feb 21, 2016 at 22:55
  • Thanks for pointing me in the right direction. There were old domain controllers and domains which I have just removed using metadata cleanup.
    – Ash
    Feb 22, 2016 at 0:49
  • What that the server holding the schema master? Make sure all the FSMO roles holders are valid (run "Netdom query fsmo" to validate)
    – Lex
    Feb 22, 2016 at 1:02
  • Yep all FMSO roles are on the required DC.
    – Ash
    Feb 22, 2016 at 2:37

1 Answer 1


Issue due to replication failures with old domain controllers that no longer exist.

Needed to remove orphaned domain controllers and domains. I used the following guides:




  • the Petri.com link is super-helpful, thanks! Apr 26, 2017 at 14:32

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