Error loop on reboot

[kpanic]

Oftentimes when issued manually to reboot, the system would close up all the processes but somehow fail to proceed. When given input, the terminal would show up, with the last line telling the system is initiating reboot, but further input returns the original black screen, which we had escaped. Further input rolls back to the same terminal sequence, appearing to load again each time anew.

If you are trying to shutdown, reboot or startup and
still find out just a black screen, try this:

Press CTRL+ALT+F2
You should get a login prompt. Login and type 'sudo su'
Then command:

Code:

mount | grep /dev/sd

If it gives some drives still mounted, then
try to unmount them and if it fails, remount them read-only
by commanding something like: 'sync; mount -o remount,ro /dev/sdX'
where X is the partition you are trying to unmount.

So, first try to unmount the unmounted partitions, if some or all
of them fail, then try to remount them read-only, like said above.
Let's say it succeeded, then just command:

Code:

sync; init 0

and reboot...

But, if it did not succeed, then try:

Code:

sync; mount -o remount,rw / ;

There are certain race-type bugs in Ubuntu systemd services which cause
these kinds of problems. But, let's fix them, right?