Why aren't my Domain Controllers Global Catalogs?
Today was interesting. A customer just promoted some new Server 2019 DCs, but those DCs wouldn't become global catalogs. They were logging this event in the Applications and Services >> Directory Service Log. Event 1578, ActiveDirectory_DomainService: "Promotion of the local domain controller to a global catalog has been delayed because the directory partition occupancy requirements have not been met." In another event... "As a precondition to becoming a global catalog server, a domain controller must host a read-only replica of all directory partitions in the forest. This event occurs because a Knowledge Consistency Checker (KCC) task has not been completed or because the domain controller cannot add a replica of the directory partition because of unavailable source domain controllers. An attempt to add the replica will occur again at the next KCC interval." Digging in, the underlying problem is they had an old "abandoned" child domain in AD.
