Hum I started to write answers to different emails, but it looks like I messed things between an actual problem (A non-critical hard disk that crashed with no "nofail" option in the fstab) and my tries afterwards to boot in rescue/emergency mode. To answer to Gaëtan, the message that I saw was exactly the one in /usr/lib/systemd/system/{rescue,emergency}.service I know the difference is important but I cannot remember which one it was (most probably it's the one corresponding to what happens when things go bad) Mainly, I made a confusion with what is "usual" in Ubuntu in the grub, that is to have a line for normal booting, and one line for "emergency", that tries as hard as possible to reach a (root) shell even when things go badly. Now I know that I'll have to configure this behavior somehow manually (?) Thanks all for your help! Best regards, -- Ismael