Shut Down Quickly - A stop job is running

I have used systemd for 5 months. Sometimes I get this problem. To reduce the delay from the default value 90s (1min30s), it is in the /etc/systemd/system.conf file:

#DefaultTimeoutStartSec=90s
#DefaultTimeoutStopSec=90s

Uncomment these line and change to any value you want. This solution just reduce time you have to wait. You should check your virtualbox daemon.

Second solution is install watchdog and enable it. It works for many people but it not works for me.

P/s: If you want to force poweroff. Let have a look at systemctl manpage.