Using Debian Stretch x86_64. I don't use a greeter like lightdm. I just log in at the virtual terminal, then startx (xfce desktop). I like to use multiple accounts (running X) at the same time on different virtual terminals (eg. ctrl-alt-f1 ctrl-alt-f2) All is fine until I exit (shutdown) one X session, then the other running X session freezes and then after a little while crashes. Any ideas on how to find or diagnose what's causing this issue are much appreciated. Thanks
Maybe you can find more information in the log messages. /var/log/Xorg.x.log gives information about the X server. Or try journalctl to read all log messages.
Floris