A stop job is running for session c1 of user...

article #1226, updated 109 days ago

This notice can be seen at shutdown of recent Linux. The only thorough solution this writer has seen, is to use the ‘watchdog’ service to get rid of hanging processes. You’ll need to compile, perhaps using ‘yay’, on Arch and derivatives:

yay -S watchdog
sudo systemctl enable watchdog.service
sudo systemctl start watchdog.service