failed upgrade from 12.04 to 14.04

[Stephen M. Webb]

On 08/22/2014 11:36 AM, Doug Stewart wrote:
> 
> I believe I am using lightdm. I say this because in /var/log/lightdm there is a log file with the correct date on it.
> 
> Looking in /var/log/lightd/lightdm.log  and compering it to my 12.04 file I see almost the same thing. I don't see any where
> that there was an error.   It reported that I did try to start a Ubuntu session.
> 
> What next??

Well, LightDM is going to try to execute a session through some wrappers scripts that dump their diagnostics into
~/.xsession-errors which is another place to look for problems.

During session startup all of the scripts in /etc/X11/Xsession.d get sourced.  If there is a bad script there it would
wreak havoc with any X11-based session.  Because they're in /etc they're config files which do not get replaced or
removed during an upgrade, so I would weight those scripts heavily in searching for problems.

One of the last things that gets done during startup for many DEs is to run "upstart" to handle the various services.
So, the next step I would suggest is to get to a console and remove all the log files in ~/.cache/upstart and try
logging in again, then check to make sure there are log files again.  If not, the break is before upstart gets started.

Also, if upstart is running, a 'ps fax' command will show 'init --user' will be a child process of lightdm, like below.

 1293 ?        SLsl   0:00 lightdm
 1365 tty7     Rs+   85:19  \_ /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
 2139 ?        Sl     0:00  \_ lightdm --session-child 12 19
 2534 ?        Ss     0:17      \_ init --user
 2719 ?        Ss     0:00          \_ ssh-agent -s
 2729 ?        Ss     0:36          \_ dbus-daemon --fork --session --address=unix:abstract=/tmp/dbus-vu8i6frZ7E
 ...                  ...           \_ ...

Note this shows the lightdm process, which runs as root and displays the login screen and authenticates the user, spawns
a privileged X server process (which required root privs to get at the hardware) and an unprivileged "session child"
process that runs a user-level upstart (init) to control the user session.  Just so you know.

If you do not see that for the Ubuntu (Unity), Gnome, or LXDE desktops it's likely the problem is in the Xsession.d
scripts (also other DEs, I only know those three for certain).

So, in summary:

(1) check ~/.xsession-errors for signs of badness
(2) clean out ~/.cache/upstart, log in, and check that directory for nefarious symptoms
(3) check what processes are running when the session fails to start

The results will determine the next steps to take.

-- 
Stephen M. Webb  <stephen at ubuntu.com>
https://launchpad.net/~bregma