So I was upgrading my home server first from Maverick Meerkat to Natty Narwhal, and then from Natty to Oneric Ocelot.
It is not a plain desktop installation, as back in the time I installed Ubuntu Server and then built upon it adding Gnome without the useless stuff that comes with the ubuntu-desktop package.
Anyway, after upgrading to Oneiric the X interface went away, all I saw was the boot messages text by the kernel up to the Apache2 start, and nothing else. SSH was still accessible so I could go through it, but you could still use recovery console to access the system if you don’t have remote terminal capability installed.
Checking with dmesg I saw these error messages:
[ 24.974182] gdm-simple-
slav : segfault at 0 ip 002945b7 sp bfe9b6c8 error 4 in libnss_ compat- 2.13.so[ 291000+ 6000] [ 38.598946] gdm-simple- slav : segfault at 0 ip 00a3b5b7 sp bf9c35c8 error 4 in libnss_ compat- 2.13.so[ a38000+ 6000] [ 39.562834] gdm-simple- slav : segfault at 0 ip 005eb5b7 sp bff72138 error 4 in libnss_ compat- 2.13.so[ 5e8000+ 6000]
Upgrading again, via SSH, to Precise Pangolin didn’t solve the problem, so I googled aroung and found this bug on launchpad.
Apparently, the autologin feature prevents GDM from going on and just hangs there.
Briefly, what I did and worked in my case (mileage may vary) was:
sudo add-apt-repository ppa:gnome3-team/gnome3 sudo add-apt-repository ppa:ubuntugnometeam/ppa-gen sudo apt-get update sudo apt-get dist-upgrade sudo mv /etc/gdm/custom.conf /etc/gdm/custom.conf.off
The last line is the command that removes the autologin (by renaming the conf file that activates it), after doing this and rebooting I was showed the login screen.