Cannot login via Unity login screen after upgrade to 12.04

Question

Logging in via the shell accessed through Ctrl+Alt-F1 and logging in as guest via the graphical user interface work 0O

When I try to log into my standard user account via the graphical interface, the screen flashes to black for a couple of seconds and bumps me back to a pristine login screen. Entering a wrong password for my user account yields the standard error message - my user account and credential verification seem to be OK.

I suppose that my individual graphics configuration causes problems ... I'm not sure how to reset that. I've tried stopping the UI via

sudo service lightdm stop

executed

sudo nvidia-xconfig

and restarted the UI

sudo service lightdm start

to no avail.

My workstation has a Nvidia GeForce 560-448 graphics card. I've tried getting this fixed with the latest Nvidia 64-bit drivers (cURL'ed from the official website), that is 295.49 and the latest beta driver 302.07.

Anybody have an idea how to get this fixed? Your help is appreciated :)

Solution 1

I've changed the display manager from the default LightDM to GDM by installing latter via sudo apt-get install gdm. With GDM set as new display manager (execute sudo dpkg-reconfigure gdm if you couldn't set GDM as display manager during installation), I could log in via the old-school graphical login screen it presented me with after a reboot.

Once logged in, I reset my display manager to LightDM by executing sudo dpkg-reconfigure lightdm. After another reboot, things were back to normal: I can log in via the distribution's standard login UI, now.

Solution 2

Check after 12.04 upgrade: can't log in although password is correct. At the bottom of question you'll see:

sudo rm /home/<username>/.Xauthority*
sudo apt-get install --reinstall xorg
sudo reboot

That worked perfectly to me.

Solution 3

sudo useradd -m username1
sudo passwd -m username1

This reset everything back to where I could log in again.

Solution 4

This is weird.

I've been running 12.04 for awhile now (a few months) without issue. I haven't logged into the GUI in awhile (I typically shell in or use Webmin). Today, I tried to log into the machine via the GUI with my non-root account, it acts like it's trying to load up the desktop then bounces me back. I'm able to shell into the account without issue.

I created a new account and I can log in via the GUI, but the old account still doesn't work.

I stopped lightdm and started gdm and I was able to gain access into my old account via the GUI.

lightdm is probably choking on something...I've no idea what, since the account home directory of the old account is pretty empty, with the acception of hidden files. I suspect that lightdm is choking on a hidden file.

I was just going to leave it alone and continue to use gdm, but looked at the above possible solution.

Ran sudo rm /home/username/.Xauthority* and didn't reinstall xorg. I stopped gdm and started lightdm. Then I attempted to log into the old account again...with success!

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Comments

[codesurgeon]

I've installed GDM via 'sudo apt-get install gdm' and set it as default display manager vs. lightdm After a reboot I can log into my user account via GDM's old style login screen. Even though I'm happy this lets me get back to work, I'd love to know why lightdm is acting flaky and how to resolve this properly.

[Web-E]

This should help you diagnostic the problem - askubuntu.com/questions/65852/cannot-login-to-my-user-accoun‌​t .

[codesurgeon]

Thank you for the pointer. I've just set lightdm as display manager again with 'sudo dpkg-reconfigure lightdm'. I can log in via the standard login screen now.

[Aquarius Power]

I have to say also that, I lost ctrl+alt+f1 again, screen is blanked... just to complete my initial post...

[pettazz]

I tried the same thing, but ended up back at the login loop when I restored lightdm, so now I'm just using gdm and everything is okay. Close enough.