Upgraded from 12.04 to 14.04...upgrade worked but ran into permission problems mounting usb stick and launching applications. Attempting to fix this I edited and saved lightdm....am now stuck in login loop when I attempt to login using owner account...only other account is guest which allows login but has no permissions .....how can I re-edit lightdm file to remove my changes using the guest account?

2 Answers 2


Login using the TTYs: Press CtrlAltF2 (or F1toF6) to get to a login prompt, login, then use sudo nano to edit the configuration files.


The easy way to do that is by reconfigure lightdm using dpkg:

so open a Terminal TTY Ctrl+Alt+F2 and do the folowing;

stop lightdm sudo service lightdm stop

reconfigure sudo dpkg-reconfigure lightdm

start lightdm sudo service lightdm start

it shoultd work fine if not move to the hard way by trying to undo by urself the changes of lightdm configuration you'll find it in /etc/lightdm/lightdm.conf good luck

and you may also check the permissions of lightdm or your profile (chown)

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