Failed to start session (Error opening file '/var/lib/lightdm/.Xauthority': Permission denied)

[jpfle]

LightDM was working with Oneiric, but after some updates, it stopped working. Boot stops to checking battery state (I have a netbook). As a workaround, I can use either GDM or KDM. Content of file "/var/log/lightdm/lightdm.log" is:

[+0.03s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.03s] DEBUG: Starting Light Display Manager 1.0.1, UID=0 PID=1044
[+0.03s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf
[+0.03s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.03s] 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
[+0.04s] DEBUG: X server :0 will replace Plymouth
[+0.08s] DEBUG: Using VT 7
[+0.08s] DEBUG: Activating VT 7
[+0.08s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+0.09s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+0.09s] DEBUG: Launching X Server
[+0.09s] DEBUG: Launching process 1081: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch -background none
[+0.09s] DEBUG: Waiting for ready signal from X server :0
[+0.09s] DEBUG: Acquired bus name
[+0.09s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+4.62s] DEBUG: Got signal 10 from process 1081
[+4.62s] DEBUG: Got signal from X server :0
[+4.62s] DEBUG: Stopping Plymouth, X server is ready
[+4.65s] DEBUG: Connecting to XServer :0
[+4.66s] DEBUG: Starting greeter session
[+5.43s] DEBUG: pam_start("lightdm-autologin", "lightdm") -> (0x82cff00, 0)
[+5.44s] DEBUG: Starting session unity-greeter as user lightdm logging to /var/log/lightdm/x-0-greeter.log
[+5.48s] DEBUG: pam_authenticate(0x82cff00, 0) -> 0 (Success)
[+5.48s] DEBUG: pam_acct_mgmt(0x82cff00, 0) -> 0 (Success)
[+5.48s] DEBUG: Launching session
[+5.50s] DEBUG: pam_set_item(0x82cff00, 3, ":0") -> 0 (Success)
[+5.61s] DEBUG: pam_open_session(0x82cff00, 0) -> 0 (Success)
[+6.04s] DEBUG: Opened ConsoleKit session 193152f56cf0db270b0c38b70000000e-1318615057.380498-941759704
[+6.04s] DEBUG: Dropping privileges to uid 107
[+6.04s] DEBUG: Adding session authority to /var/lib/lightdm/.Xauthority
[+6.04s] WARNING: Error reading existing Xauthority: Error opening file: Permission denied
[+6.04s] DEBUG: Restoring privileges
[+6.04s] WARNING: Failed to write authority: Error opening file '/var/lib/lightdm/.Xauthority': Permission denied
[+6.04s] DEBUG: Failed to start greeter session
[+6.04s] DEBUG: Stopping display
[+6.04s] DEBUG: Sending signal 15 to process 1081
[+6.36s] DEBUG: Process 1081 exited with return value 0
[+6.36s] DEBUG: X server stopped
[+6.36s] DEBUG: Removing X server authority /var/run/lightdm/root/:0
[+6.36s] DEBUG: Releasing VT 7
[+6.36s] DEBUG: Display server stopped
[+6.36s] DEBUG: Display stopped
[+6.36s] DEBUG: Stopping X local seat, failed to start a display
[+6.36s] DEBUG: Stopping seat
[+6.36s] DEBUG: Seat stopped
[+6.36s] DEBUG: Stopping lightdm, required seat has stopped
[+6.36s] DEBUG: Stopping display manager
[+6.36s] DEBUG: Display manager stopped
[+6.36s] DEBUG: Stopping Light Display Manager

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: lightdm 1.0.1-0ubuntu6
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic i686
ApportVersion: 1.23-0ubuntu3
Architecture: i386
Date: Tue Oct 18 00:18:29 2011
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
SourcePackage: lightdm
UpgradeStatus: Upgraded to oneiric on 2011-08-23 (55 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.