lightdm failed to find session configuration ubuntu

[maclenin]

ISSUE:

I cannot get past the login screen, either as "user" or "guest" when attempting to start-up ubuntu 13.10.

Essentially, after laptop (HP-Compaq 2510p) power-up, the lightdm page / login prompt is presented. Once the password is entered (i.e. no autologin), the password entry field clears and there is no progress to the desktop page / ubuntu session. Shutdown, clock, sound, language and network manager icons all appear on the upper right of the lightdm login page and seem to function properly. The computer name appears on the upper left.

I am able to toggle between a terminal session (ctrl+alt+f1) and lightdm login page (ctrl+alt+f7), however, I am not able to launch any graphical applications - such as thunar, firefox, leafpad, etc from the terminal.... For example, when trying to launch thunar via the terminal, it shows:

Thunar: Cannot open display:
NOTES:

1. I had been working to re-install libimobiledevice - just prior to experiencing this problem. I had installed libimobiledevice-1.1.6 and THEN completed removal of an older version of libimobiledevice and related items (gvfs-backends, libgpod-common, libgpod4, upower) via the software-center. Perhaps, there is some connection between the libimobiledevice removal and the larger issue?

2. A, perhaps, relevant snippet from /var/log/lightdm/lightdm.log shows:

[x] DEBUG: Session pid=y: Authentication complete with return value 0: Success
[x] DEBUG: Session pid=y: Authenticate result for user z: Success
[x] DEBUG: Session pid=y: User z authorized
[x] DEBUG: Session pid=y: Greeter requests session ubuntu
[x] DEBUG: Writing /home/z/.dmrc
[x] DEBUG: Seat: Failed to find session configuration ubuntu
[x] DEBUG: Seat: Can't find session 'ubuntu'
2.a. A cat /home/z/.dmrc shows:

[Desktop]
Session=ubuntu
3. All had been working well up until restart immediately after removal of the old libimobiledevice.

Thanks for any guidance!

[steeldriver]

What are the contents of your /usr/share/xsessions directory? does it contain a ubuntu.desktop session file?

[maclenin]

steeldriver!

Thanks for the reply.

The only quasi-reference I have to xsessions - as determined via locate is: /etc/upstart-xsessions
The only quasi-reference I have to ubuntu.desktop - as determined via locate is: /usr/share/app-install/desktop/edubuntu.desktop

Thoughts?

[steeldriver]

Hmm... what about



dpkg -l gnome-session


It's starting to sound like it got uninstalled somehow

[maclenin]

Running dpkg -l gnome-session shows, essentially:

<none> and (no description available)
The desktop environment that's failing was whatever the default 13.10 ubuntu install environment is - is it unity?

When I run unity from the command line, I get:

WARNING: no DISPLAY variable set, setting it to :0
compiz (core) - Info: Loading plugin: core
unity-panel-service: no process found
compiz (core) - Info: Starting plugin: core
Invalid MIT-MAGIC-COOKIE-1 keycompiz (core) - Fatal: Couldn't open display :0
compiz (core) - Info: Stopping plugin: core
compiz (core) - Info: Unloading plugin: core
Do you think those applications removed along with libimobiledevice could have played a role?

Thanks, again, for the suggestions.

[steeldriver]

I would suspect that removal of gvfs-backends is the culprit - consider



$ apt-cache rdepends --recurse gvfs-backends | grep gnome-session
gnome-session-flashback
gnome-session-flashback
gnome-session
.
.
.


You could *try*



sudo apt-get install --reinstall gnome-session


or perhaps even



sudo apt-get install --reinstall ubuntu-desktop


although tbh if ubuntu-desktop was removed I'm kind of surprised you still have a GUI (lightdm?) login screen

[maclenin]

Bingo!

Thanks, steeldriver, the install --reinstall of gnome-session / gvfs-backends was the ticket, it seems. I had, actually, considered that gvfs-backends might be involved but hadn't the ken to run apt-cache rdepends --recurse gvfs-backends | grep gnome-session to test my therory....

Which, begs the question, for a separate thread, perhaps - when preparing to install a new version of libimobiledevice, shouldn't one (be able to) remove the old version, first? I didn't know that libimobiledevice (and dependecies) were (so) hardwired into the fabric of the desktop....

Thanks, again!