Today while trying to demote a domain controller I received an error:
The directory services is missing mandatory configuration information, and is unable to determine the ownership of floating single-master operation roles.
Running dcdiag /v yielded an error like the following:
Ownership of the following FSMO role is set to a server which is deleted or does not exist. Operations which require contacting a FSMO operation master will fail until this condition is corrected. FSMO Role: CN=Infrastructure,DC=DomainDnsZones,DC=mydomain,DC=local FSMO Server DN: CN=NTDS Settings ADEL:464a6261-2c82-4ac1-b2b2-144d2e5e1b74,CN=SOMEOLDSERVER