Comment 3 for bug 1594233

This shouldn't happen and I have no idea what's causing the bug. But if you're still on Ubuntu 14.04 and haven't upgraded using a live USB/DVD, could you please try running `sudo do-release-upgrade` and `sudo do-release-upgrade -d` in Terminal and advise as to the results? Don't use the `-d` flag if you're on 16.04, because that will upgrade you to Ubuntu Yakkety (the development release), but sometimes it helps if you use that when trying to upgrade to 16.04.

If that works, then hopefully the logs you've got in the bug report there will be enough for the developers to fix the original bug.