Comment 2 for bug 1484903

It hangs on quite a few different messages. Like every 2nd or 3rd Ubuntu release the shutdown process again is wasted.
It would be great to have a hard shutdown step after 30 seconds idling at least. My machine here is stuck forever.

These days it isnt the kernel acpi anymore crashing the shutdown process. We now got the beautiful upstart messing around with users. Usually it takes 1 to 2 relaese cycles for the distro to fix such a bug. Expect your pc working in 16.04 or 16.10.