Can't shutdown xubuntu after updating to 16.04

Question

I updated from Xubuntu 16.04 beta-2 to 16.04 today. And now I can't shutdown my laptop but I am able to restart. When I try it the GUI way it just logging out.
When I tried

sudo shutdown -h now

I got the following error:

Failed to start poweroff.target: Transaction is destructive.
See system logs and 'systemctl status poweroff.target' for details.

Output of /var/log/messages:

tail /var/log/messages
tail: cannot open '/var/log/messages' for reading: No such file or directory

Output of systemctl status poweroff.target

● poweroff.target - Power-Off
   Loaded: loaded (/lib/systemd/system/poweroff.target; disabled; vendor preset:
   Active: inactive (dead)
     Docs: man:systemd.special(7)

Answer 1

I have same problem in my laptop dell Inspiron 5110. After tried this, my computer shutdown normaly

sudo init 0

Answer 2

The accepted answer sudo init 0 doesn't work for me in Xubuntu based in Ubuntu 16.04.

While waiting for a patch this is how I can shutdown my laptop:

Using poweroff

• sudo poweroff -f

-f to force the computer to shutdown without contacting the init system.

Detecting the process that prevents the computer to shutdown

In my case there is always the tty process that blocks the poweroff process. So detecting it, killing the process and starting the systemctl target.

• ps aux | grep tty

  root 983 0.0 0.0 15408 1128 ? Ss 11:49 0:00 /bin/systemd-tty-ask-password-agent --wall

• Kill the process: sudo kill 983

• Shutdown the computer: First sudo systemctl start poweroff.target and if it fails execute the command again: sudo systemctl start poweroff.target.

Related questions

• Debian won't shut down (Failed to start poweroff.target: Transaction is destructive)
• Ubuntu 16.04 won't power off: poweroff.target is disabled

Answer 3

@marcanuy's answer works for me on Ubuntu 16.04. If you want to use the second method in that answer, here is a script you can put in your .bashrc to do that easily:

shutdown_workaround() {
    TTY_PID=$(ps aux | grep -v grep | grep -Po "root +\K[0-9]+(?= .*systemd-tty-ask-password-agent)")
    sudo kill $TTY_PID
    sudo systemctl start poweroff.target || sudo systemctl start poweroff.target
}