I was able to reproduce this problem in a VM. Running X and compiz under gdb, I find that compiz is dying after the X server is killed with SIGKILL.
I also see this in /var/log/syslog: Mar 25 22:31:40 trusty-upgrade kernel: [ 7167.438442] init: lightdm post-stop process (2433) killed by KILL signal There is no evidence in dmesg that this is OOM related. So something appears to be inappropriately kill -9'ing lightdm on upgrade. This is not the only process in /var/log/syslog showing as killed with SIGKILL. The first of these happens in the logs at 22:31:39. At that time, /var/log/dpkg shows these packages being configured: udisks desktop- file-utils gvfs-common gvfs-libs gvfs-daemons gvfs psmisc python-gi. /var/log/dist-upgrade/apt-term.log doesn't show anything particularly illuminating. Attaching the contents of /var/log. ** Attachment added: "logs.tar.gz" https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1555237/+attachment/4612158/+files/logs.tar.gz -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1555237 Title: Upgrade from 14.04.4→ 16.04 dies midway taking out the session. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/1555237/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
