Same problem occured to me (just after "apt-get upgrade", trying to reboot the system).
Please also see this link: http://unix.stackexchange.com/questions/274761/debian-wont-shut-down-failed-to-start-poweroff-target-transaction-is-destruct Someone there says that killing the "systemd-sleep" process can help. When I tried, my system went to sleep immediately. When I resumed it, it went back to life but the screen stayed black (I had quit my desktop session and even stopped my desktop manager, so I was on a console, no GUI was running). I tried to type "poweroff" without the screen, it didn't work, but when I hit the power button, the machine finally stopped correctly...
