I have Ubuntu 20.04 installed under WSL2 on my windows machine. I followed the instructions here to install XFCE and XRDP and change the XRDP port to work with Windows Remote Desktop.

I can connect using windows remote desktop, and I get get the XRDP login screen. The problem is when I enter my Ubuntu username and password (I've verified they're correct) and click OK, nothing happens. No error messages, nothing. I suppose it's hung because nothing (like the cancel button) works after that.

The only suspicious thing in xrdp.log is "[WARN ] local keymap file for 0x00000409 found and doesn't match built in keymap, using local keymap file" and I've read keyboard mapping can cause login to fail. But I've not had any other keyboard problems.

I found a thread here talking about fixing login problems, but it was started five years ago and am wary of applying fixes that old.

Any advice how to troubleshoot?

XRDP will hang if the user is logged in locally, even if the session is locked.

You had me all excited. Tried exiting the Ubuntu window on WSL. It's still hanging. The frustrating part is that I can't find any error messages that might help diagnose the problem. Is there a good place to look besides xrdp.log?

Maybe this should help you out. https://dev.to/avanishsubbiah/comment/lp3i. It's not that old.