Domain – Can’t rejoin server to domain after deleting it from DC

active-directorydomaindomain-controllerwindows-server-2008-r2

I have a Windows 2012 R2 Server Core machine that I was using for testing. I thought I was done with it, so I deleted the associated object from Active Directory Users and Computers. I didn't touch the machine itself.
Now I've decided I want to use the machine for more testing, but I can't get it joined to the domain again. What I've tried so far:

  1. Boot it while connected to the network, log in with domain account. It says "The security database on the server does not have a computer account for this workstation trust relationship." (That was predictable, but I included it for thoroughness).

  2. Boot it while connected to the network, log in with local admin account

    2a. If I just run through the process of joining the domain in sconfig (option 1), it says "The machine is already joined to a domain".

    2b. If I try to join a workgroup, it says "Machine is currently joined to a domain. Do you want to remove this computer from the current domain now?" I click yes, and after I give credentials, it says "Failed to join domain."

    2c. If I try to rename the computer, it says "Failed to join domain."

  3. Boot the computer while disconnected from the network. I can then log in with domain credentials. After that I connect it to the network again. I can ping the domain controller, but I still get the same errors detailed above.

In short the computer thinks it's still a member of the domain, but the domain controller has no knowledge of it, and I seem to be stuck in a catch-22. Sure, I could just reinstall Windows from scratch, but there's gotta be a better way.

Best Answer

  1. Disconnect the computer from the network.
  2. Log in with either a local or cached domain account.
  3. Make sure you know the password for an enabled local account. You'll need it later, and this will be your last chance to create one or reset a password.
  4. Change the computer to workgroup. It will ask you for a username and password for a domain admin. Fill in whatever you want; it doesn't matter because it's going to fail anyway because you're not connected to the network.
  5. Reboot as directed.
  6. Connect the computer to the network.
  7. Log in with a local account and join the computer to the domain. A cached domain account won't work. You must log in with a local account.
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