Q: My BDC lost contact with the PDC. How can I demote the BDC without the PDC?
A: UPromote will ask to contact the PDC in order to delete the machine account of the BDC. It will refuse to continue if it cannot locate the PDC.
This problem can occur if you upgrade your Active Directory domain from "mixed" mode to "native" mode while one or more NT BDCs are still present. When you do this your BDCs will lose contact with the Windows 2000/2003/2008 domain controllers.
As a workaround, if your BDC becomes orphaned you can use the following procedure to demote it:
- Temporarily disconnect the network cable.
- Promote the BDC to PDC using SRVMGR.EXE.
- Run UPromote to demote the computer to a standalone server. Because UPromote thinks the computer is a PDC, it will not attempt to contact the real PDC.
- After you are done reconnect the network cable.
- Run SRVMGR.EXE on the real PDC and manually delete the machine account for the BDC. On Active Directory delete the BDC object from the Domain Controllers folder.
Afterwards you can rejoin the computer to the domain as a member computer. See Rejoining the Same Domain.