My Ubuntu 16.04 LTS installation, probably after installing updates, now unable to start Unity after user login. It just freezes!
Google'ing won't help this time :/
I.e. OS boots, show login screen, but Unity hangs during startup and never finished it. I'm even unable to switch to the another console, system does not respond.

How to debug such kind of problems? What can i do to repair system?
I don't want to reinstall it - so Windows way it is :(

  • reboot and use journalctl -ex, then search for you process and figure out what is happening – Wissam Roujoulah Jan 8 '17 at 15:15
  • 1
    if you have closed drivers for graphics adapter dkms status. Sometimes dkms donot built the driver to a new kernel. – user192526 Jan 8 '17 at 18:14

You can not login graphically, but you can still login in text mode. Switch to the console (CtrlAltFn) and log in. Then you can look at the logs.

First, begin with the ~/.xsession-errors file in your home directory. You can also execute ls -ltra ~ | tail to see the last changes in your home. Maybe there are other log files to read? As a last resort find ~ -mmin -15 -type f will give you all the files in your home that have changed in the last 15 minutes, that may be interesting (is there a core file? a crash report? etc.)

If you don't find anything in your home directory, you can look at the system-wide log files in /var/log. Begin with /var/log/Xorg.0.log. If you find nothing, you can execute ls -ltr /var/log | tail to have a list of the log files that have changed lately. Read the one that have changed at the time you logged in (or since). You may have to sudo -s in order to look into some of these files.

  • The problem was in nouveau driver - after installation of proprietary NVidia drivers the problem disappears. – eraxillan Jan 13 '17 at 6:17

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