Upgrade from 12.04, lightdm doesn't launch the DE fully...

[mweishaa]

I think that this is my 5th or 6th upgrade of kubuntu...and no, I don't want to do a fresh install.
I am running xfce on top of kubuntu with an Nvidia video card.
So I downloaded the DVD image to upgrade locally, because last upgrade I did the day after the release came out... and it took F O R E V E R. But I couldn't figure out how to a local upgrade (grumble)... for some reason the liveCD woulnd't launch right, an issue with the noveau driver.

So I bit the bullet and spent the day letting it download the updates, and everything went pretty smoothly. But upon reboot and login (to try KDE) all I got was the background image and the X mouse cursor and couldn't do anything at all. So I restarted and tried to log into XFCE and got the same exact thing. In the console I noticed that the only thing that was running for xfce was /bin/sh /usr/sbin/lightdm-session startxfce4. I was able to manually launch xfce4-session. After that, I logged out and tried again, thinking it needed a saved session to start up... but same thing.

So now I am up and running, but not fully and something isn't right. Why wouldn't lightdm be able to launch KDE, xfce, etc? I didn't see any obvious errors in logs. I did get a "system error" dialog around apport-gtk and gsettings. But I did an update and installed the packages that came up. Any help is appreciated.

[mweishaa]

OK, I figured this out.
First I uninstalled lightdm, which removed lightdm, lightdm-greeter, and kubuntu-desktop.
Then when I re-installed lightdm, it added unity and about 96 other packages. Then I re-added kubuntu-desktop.
No joy.
But.. I saw an ibus error in the lightdm x-0-greeter.log. I didn't think much of it because there weren't any errors in the lightdm or x-0.log.
QInotifyFileSystemWatcherEngine::addPaths: inotify_add_watch failed: No such file or directory
QFileSystemWatcher: failed to add paths: /var/lib/lightdm/.config/ibus/bus
file:///usr/share/kde4/apps/lightdm-kde-greeter/themes/userbar/main.qml:135: Unable to assign [undefined] to QString usersession
lightdm-kde-greeter: Fatal IO error: client killed
I isntalled ibus, rebooted, and everything came up perfectly. I don't know much about ibus, but something needed it.

[mweishaa]

For the sake of completeness.... this never worked right.....

OK, I figured this out.
First I uninstalled lightdm, which removed lightdm, lightdm-greeter, and kubuntu-desktop.
Then when I re-installed lightdm, it added unity and about 96 other packages. Then I re-added kubuntu-desktop.
No joy.
But.. I saw an ibus error in the lightdm x-0-greeter.log. I didn't think much of it because there weren't any errors in the lightdm or x-0.log.
QInotifyFileSystemWatcherEngine::addPaths: inotify_add_watch failed: No such file or directory
QFileSystemWatcher: failed to add paths: /var/lib/lightdm/.config/ibus/bus
file:///usr/share/kde4/apps/lightdm-kde-greeter/themes/userbar/main.qml:135: Unable to assign [undefined] to QString usersession
lightdm-kde-greeter: Fatal IO error: client killed
I isntalled ibus, rebooted, and everything came up perfectly. I don't know much about ibus, but something needed it.

I thought I had it solved, but it never worked right.
After a reboot, lightdm wouldn't launch xcfe4 correctly. I could see by going to tty1 that it thought it launched it, but it didn't work.
If I went to tty1 and typed "xfce4-session --display :0" it would start up fine. I finally got tired of doing that, and I just installed gdm and kdm, then set kdm as my default dm.
Works fine now. No clue why lightdm refused to work right, but there you have it. Maybe because I'm on Kubuntu running xfce?

[Teunis]

I see you like a challenge

But I generally don't do more than a single upgrade before reinstalling, it's not worth the hassle.
LightDM has only recently become the default display manager so somewhere during your upgrades your system had a change from kdm to LightDM and I can imagine all kinds of issues...