Comment 6 for bug 438789

Hi
I had the Same bug...

 I was connected with root user (allowroot=true in gdm.conf),
upgrade launched with a : # nohup update-manager -d &

After automatic dpkg at the post installation and a reboot, then ... all upgrade is ok !

I just noticed that in /etc/gdm file gdm.conf was renamed to gdm.conf.dpkg-bak (and -old)
gdm now works without gdm.conf (///=> custom.conf)