I had a similar issue..
to get it working for me I edited my xrdp.ini
by runing
sudo gedit /etc/xrdp/xrdp.ini
then added the below to the list for my set up:
[xrdp8]
name=Reconnect
lib=libvnc.so
username=ask
password=ask
ip=127.0.0.1
port=5910
I assume yours would be the same but with port=5900
I first log in to my machine usung the default sesman-Xvnc connection option in the 'Login to xrdp' 'Module' drop-down list..
This creates the original session that i can then log back into later by selecting the Reconnect option i have created which should now show in the 'Login to xrdp' 'Module' drop-down.
All my open programs, windows and files are just as i left them in the first session when i log back in using this..
I can access this same session again from any of my other Windows PC's Remote Desktop Connection clients by again selecting Reconnect in the Xrdp login 'Module' drop-down.
Best Answer
Just a guess
If you are running Xubuntu 18.04.2 or 18.04.3, you might be affected by a know issue with xRDP...
If you have installed xrdp package manually on your system from xubuntu repository, xorgxrdp package is not installed because package dependencies issues...
Try to install the new xorgxrdp-hwe-18.04 package and try again
to install the package, execute the following command
We assume that you have already installed xrdp package on your system...
Hope this help till next time See ya