How to troubleshoot "failed to load session" errors?

Question

On the upgrade from 11.10 to 12.04, my XMonad + Unity configuration no longer works. When I attempt to log into this session, I get "failed to load session 'xmonad'". Where can I look to figure out what's going wrong?

Solution 1

What worked for me was to remove the references to unity-2d-launcher entirely from my /usr/share/gnome-session/sessions/xmonad.session (which I had configured for 11.10 the way Mark Hansen suggested):

[GNOME Session]
Name=Xmonad Unity
RequiredComponents=gnome-settings-daemon;
RequiredProviders=windowmanager;panel;
DefaultProvider-windowmanager=xmonad
DefaultProvider-panel=unity-2d-panel

I always use the shellPrompt instead of the unity launcher anyway, so I don't miss the launcher at all.

Solution 2

I was able to get the XMonad + Unity configuration to work. I examined the relevant configuration files in /usr/share/xsessions/ and /usr/share/gnome-session/sessions/ (for more info see http://markhansen.co.nz/xmonad-ubuntu-oneiric/), and tried to run the various executables they reference. I thus discovered "gnome-panel" had been uninstalled on the upgrade, so I reinstalled it.

Solution 3

The problem is that Unity-2d-launcher no longer exists in Precise. You can change it to unity-2d-shell in gnome-session/sessions/xmonad.session and in ~/.xmonad/xmonad.hs

However, even after doing this, I'm seeing a lot of weird behaviour.

Solution 4

Possibly relevant: I recently upgraded and found I needed to delete the file ~/.xmonad/xmonad-x86_64-linux, and all was fine. I run gnome + xmonad, but this step is relevant to any upgrade. See here for more notes on my experience.

Solution 5

The best place to look would be in ~/.xsession-errors you could also try /var/log/syslog.

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Comments

[Raptrex]

I installed gnome-panel and I still get failed to load session error