Comment 4 for bug 560175

I also discovered this issue (or something similar) in Ubuntu 14.04.
This is an old bug, but I will comment here instead of reporting a new bug.

When I run "sudo shutdown now" or "sudo telinit 1" to go to single-user mode, the Plymouth splashscreen appears briefly, but then a black screen appears with no text (there should be a root console there).
The root console is there however, but invisible, because typing "telinit 2" blindly and then pressing <Enter> returns the system to the normal mode.

If I disable the splashscreen (by removing the "splash" kernel parameter from the GRUB menu), switching to single-user mode works correctly. So, this is definitely a bug in Plymouth!
I can't reproduce this bug is an VirtualBox VM, however (maybe Plymouth doesn't work correctly there).
I must say that I'm using a laptop with Optimus graphics (using bumblebee). Don't know if that could have anything to do with this bug.

Booting into recovery mode works fine.

Another problem: switching to single-user mode kills all the consoles (tty1-tty6), but returning to normal mode doesn't restart them (lightdm is restarted correctly). I think this could be a very big problem on a server.