I installed xrdp via sudo apt install xrdp, but when connecting from a domain-joined Windows 10 computer I got a black screen after authenticating through the xorg session login.

After much failed sleuthing, I think I figured it out:

  1. Terminate any open RDP attempts into Ubuntu.
  2. Log out of your Ubuntu session.
  3. Run mstsc.exe from Windows back into Ubuntu — it should now be at the Ubuntu login screen and should connect successfully this time.

Root cause: unknown/not fully understood.