Had a problem after an update that when I force a restart or a shutdown on my server, it hangs on the last part of the process.
To fix my problem, I had to edit the /etc/default/grub config file and added acpi=force apm=power_off to the config line, between the double quotation marks…
do a update-grub after saving then reboot one more time.. ( force sa restart when it hangs )
After the restart, try another reboot, it should work now without hanging.
Source of the fix is from Here