I'm building a custom live Ubuntu Gnome 3.12.2 based, Only if I create a new user, set password and add him to sudo group,

setting by dpkg-reconfigure GDM ad default greeter, obtain a black screen and going to the first console appear "authentication failure" message.

otherwise, using dpkg-reconfigure and select the lightdm as default greeter all work fine: the greeter show the login screen and the user is able to authenticate.

Instead if I do not create any user, and set GDM ad default greeter, all work fine, but no login screen appear and the user goes directly to its desktop.

For build the iso I'm using the Ubuntu directive: https://help.ubuntu.com/community/LiveCDCustomization

  • Please edit your question with the output of sudo apt-get install ubuntu-desktop
    – David
    Oct 30 '15 at 11:54

The reason

dpkg-reconfigure gdm

Isn't working is because you are missing the 'sudo' in front of it. It should be

sudo apt-get install gdm
sudo dpkg-reconfigure gdm

Then use the down key to select GDM and use Enter to select GDM. Then do a

sudo reboot now

And it'll be fixed

  • Thanks David for your reply, but the question is a bit 'more complicated. On chroot environment I'm root and do not need to invoke sudo.I've write to GDM and Ubuntu Gnome mailing list and none of them was able to respond. Oct 30 '15 at 11:09

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