Ubuntu – Ubuntu 12.04 shutdown does not finish

By default, the latest ubuntu install (12.04.2, and few others behind) hides messages and shows a nice animated image (splash) in a fancy resolution.

To make sure to view the console and possibly see what's hanging behind that dark screen:

/etc/default/grub (edit & save):

# find line below and put a # in front of it
# GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
# and put this one:
GRUB_CMDLINE_LINUX_DEFAULT="nomodeset"

Now update grub boot entries with these new defaults:

you@yourmachine:~$ sudo update-grub

And at your next start/shutdown process, you should see message lines with [ OK ] or [ ERROR ] or something wrong following it's title:

* Starting network shares                   [ OK ]
* Starting mysql server                     [ OK ]
* ...later when shutting down...
* Stopping mysql server                     [ OK ]
* Not Stopping something like it should     [    ]

nomodeset: You usually can toggle between the splash screen and the console messages with Esc key, but some video cards or lack of drivers can't handle the mode/capacities the boot process is using. nomodeset ensures it's using basic common capacities and makes sure you see messages (provided you don't press ALT-F1 to F7 during boot/shutdown to view other terminals than the one used for services startup/shutdown).

Edit: You can also try without nomodeset if you run into troubles starting X. GRUB_CMDLINE_LINUX_DEFAULT=""