Take the 2-minute tour ×
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free, no registration required.

After entering login info in lightdm, screen blacks out for a second and returns back to the login screen again. However, I'm able to login through TTY and gdm without any problem.

As the log file at /var/log/lightdm/lightdm.log says, the problem is "authentication failure" but I can't figure out how to solve it.

[+0.01s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.01s] DEBUG: Starting Light Display Manager 1.4.0, UID=0 PID=2279
[+0.01s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf
[+0.01s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.02s] DEBUG: Registered seat module xlocal
[+0.03s] DEBUG: Registered seat module xremote
[+0.03s] DEBUG: Adding default seat
[+0.03s] DEBUG: Starting seat
[+0.03s] DEBUG: Starting new display for greeter
[+0.03s] DEBUG: Starting local X display
[+0.03s] DEBUG: Using VT 7
[+0.03s] DEBUG: Activating VT 7
[+0.03s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+0.03s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+0.03s] DEBUG: Launching X Server
[+0.03s] DEBUG: Launching process 2287: /usr/bin/X :0 -core -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.03s] DEBUG: Waiting for ready signal from X server :0
[+0.03s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.03s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.18s] DEBUG: Got signal 10 from process 2287
[+0.18s] DEBUG: Got signal from X server :0
[+0.18s] DEBUG: Connecting to XServer :0
[+0.18s] DEBUG: Starting greeter
[+0.18s] DEBUG: Started session 2291 with service 'lightdm-greeter', username 'lightdm'
[+0.22s] DEBUG: Session 2291 authentication complete with return value 0: Success
[+0.22s] DEBUG: Greeter authorized
[+0.22s] DEBUG: Logging to /var/log/lightdm/x-0-greeter.log
[+0.25s] DEBUG: Session 2291 running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/unity-greeter
[+0.65s] DEBUG: Greeter connected version=1.4.0
[+0.65s] DEBUG: Greeter connected, display is ready
[+0.65s] DEBUG: New display ready, switching to it
[+0.65s] DEBUG: Activating VT 7
[+3.16s] DEBUG: Greeter start authentication for amir
[+3.16s] DEBUG: Started session 2383 with service 'lightdm', username 'amir'
[+3.26s] DEBUG: Greeter start authentication for amir
[+3.26s] DEBUG: Session 2383: Sending SIGTERM
[+3.26s] DEBUG: Started session 2385 with service 'lightdm', username 'amir'
[+3.26s] DEBUG: Session 2383 terminated with signal 15
[+3.26s] DEBUG: Session 2383 failed during authentication
[+3.27s] DEBUG: Session 2385 got 1 message(s) from PAM
[+3.27s] DEBUG: Prompt greeter with 1 message(s)
[+8.48s] DEBUG: Continue authentication
[+8.50s] DEBUG: Session 2385 authentication complete with return value 0: Success
[+8.50s] DEBUG: Authenticate result for user amir: Success
[+8.51s] DEBUG: User amir authorized
[+8.52s] DEBUG: Greeter requests session xubuntu
[+8.52s] DEBUG: Using session xubuntu
[+8.52s] DEBUG: Stopping greeter
[+8.52s] DEBUG: Session 2291: Sending SIGTERM
[+8.76s] DEBUG: Session 2291 exited with return value 0
[+8.76s] DEBUG: Greeter quit
[+8.77s] DEBUG: Dropping privileges to uid 1000
[+8.77s] DEBUG: Calling setresgid
[+8.77s] DEBUG: Calling setresuid
[+8.86s] DEBUG: Restoring privileges
[+8.86s] DEBUG: Calling setresuid
[+8.86s] DEBUG: Calling setresgid
[+8.87s] DEBUG: Dropping privileges to uid 1000
[+8.87s] DEBUG: Calling setresgid
[+8.87s] DEBUG: Calling setresuid
[+8.87s] DEBUG: Writing /home/amir/.dmrc
[+9.07s] DEBUG: Restoring privileges
[+9.07s] DEBUG: Calling setresuid
[+9.07s] DEBUG: Calling setresgid
[+9.28s] DEBUG: Starting session xubuntu as user amir
[+9.28s] DEBUG: Session 2385 running command /usr/sbin/lightdm-session startxfce4
[+9.29s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session0
[+9.40s] DEBUG: Session 2385 exited with return value 1
[+9.40s] DEBUG: User session quit
[+9.40s] DEBUG: Stopping display
[+9.40s] DEBUG: Sending signal 15 to process 2287
[+10.19s] DEBUG: Process 2287 exited with return value 0
[+10.19s] DEBUG: X server stopped
[+10.19s] DEBUG: Removing X server authority /var/run/lightdm/root/:0
[+10.19s] DEBUG: Releasing VT 7
[+10.19s] DEBUG: Display server stopped
[+10.19s] DEBUG: Display stopped
[+10.19s] DEBUG: Active display stopped, switching to greeter
[+10.19s] DEBUG: Switching to greeter
[+10.19s] DEBUG: Starting new display for greeter
[+10.19s] DEBUG: Starting local X display
[+10.19s] DEBUG: Using VT 7
[+10.19s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+10.19s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+10.19s] DEBUG: Launching X Server
[+10.19s] DEBUG: Launching process 2494: /usr/bin/X :0 -core -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+10.19s] DEBUG: Waiting for ready signal from X server :0
[+10.34s] DEBUG: Got signal 10 from process 2494
[+10.34s] DEBUG: Got signal from X server :0
[+10.34s] DEBUG: Connecting to XServer :0
[+10.34s] DEBUG: Starting greeter
[+10.34s] DEBUG: Started session 2497 with service 'lightdm-greeter', username 'lightdm'
[+10.36s] DEBUG: Session 2497 authentication complete with return value 0: Success
[+10.36s] DEBUG: Greeter authorized
[+10.36s] DEBUG: Logging to /var/log/lightdm/x-0-greeter.log
[+10.36s] DEBUG: Session 2497 running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/unity-greeter
[+10.63s] DEBUG: Greeter connected version=1.4.0
[+10.63s] DEBUG: Greeter connected, display is ready
[+10.63s] DEBUG: New display ready, switching to it
[+10.63s] DEBUG: Activating VT 7
[+10.63s] DEBUG: Stopping greeter display being switched from
[+10.92s] DEBUG: Greeter start authentication for amir
[+10.92s] DEBUG: Started session 2582 with service 'lightdm', username 'amir'
[+10.92s] DEBUG: Session 2582 got 1 message(s) from PAM
[+10.92s] DEBUG: Prompt greeter with 1 message(s)
[+11.20s] DEBUG: Greeter start authentication for amir
[+11.20s] DEBUG: Session 2582: Sending SIGTERM
[+11.20s] DEBUG: Started session 2584 with service 'lightdm', username 'amir'
[+11.20s] DEBUG: Session 2582 terminated with signal 15
[+11.20s] DEBUG: Session 2582 failed during authentication
[+11.21s] DEBUG: Session 2584 got 1 message(s) from PAM
[+11.21s] DEBUG: Prompt greeter with 1 message(s)
[+14.61s] DEBUG: Greeter closed communication channel
[+59.09s] DEBUG: Continue authentication
[+59.11s] DEBUG: Got signal 15 from process 1
[+59.11s] DEBUG: Caught Terminated signal, shutting down
[+59.11s] DEBUG: Stopping display manager
[+59.11s] DEBUG: Stopping seat
[+59.11s] DEBUG: Stopping display
[+59.11s] DEBUG: Session 2497: Sending SIGTERM
[+59.11s] DEBUG: Session 2584 terminated with signal 15
[+59.11s] DEBUG: Session 2584 failed during authentication
[+59.11s] DEBUG: Authenticate result for user amir: Authentication stopped before completion
[+59.23s] DEBUG: Greeter closed communication channel
[+59.23s] DEBUG: Session 2497 exited with return value 0
[+59.23s] DEBUG: Greeter quit
[+59.23s] DEBUG: Sending signal 15 to process 2494
[+59.25s] DEBUG: Process 2494 exited with return value 0
[+59.25s] DEBUG: X server stopped
[+59.25s] DEBUG: Removing X server authority /var/run/lightdm/root/:0
[+59.25s] DEBUG: Releasing VT 7
[+59.25s] DEBUG: Display server stopped
[+59.25s] DEBUG: Display stopped
[+59.25s] DEBUG: Seat stopped
[+59.25s] DEBUG: Display manager stopped
[+59.25s] DEBUG: Stopping daemon
[+59.25s] DEBUG: Exiting with return value 0
share|improve this question
    
It worked! Thanks! (I can't vote up yet) –  user228382 Jun 5 at 15:36
add comment

1 Answer 1

up vote 2 down vote accepted

There's a file named .Xauthority in home directory. Changing the owner and group of this file from root to user, and changing the permissions to 664 solved the problem.

share|improve this answer
    
I had the same problem just now with saucy, and owner/group were correct, permissions originally 600, changing to 644 didn't help, but removing the file let me login. –  taneli Sep 24 '13 at 18:34
    
Yes, sometimes won't. This mostly happens to me when I try to restart the "networking" service. The last time, I changed the permissions to 666 to make it work. –  evolon Nov 25 '13 at 21:22
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.