Can you please start a debug shell as described in /usr/share/doc/systemd/README.Debian, shut down, and when it hangs run
loginctl session-status c2 > /root/session-c2.txt
Apparently there is a process in your user session which does not shut down but hangs, so we need to find out what it is. If you run "loginctl session-status c2" you see which processes are remaining together with their PIDs, and you can kill them (hopefully it should just be one or two). After rebooting, please attach /root/session-c2.txt. Thanks!
Can you please start a debug shell as described in /usr/share/ doc/systemd/ README. Debian, shut down, and when it hangs run
loginctl session-status c2 > /root/session- c2.txt
Apparently there is a process in your user session which does not shut down but hangs, so we need to find out what it is. If you run "loginctl session-status c2" you see which processes are remaining together with their PIDs, and you can kill them (hopefully it should just be one or two). After rebooting, please attach /root/session- c2.txt. Thanks!