Ubuntu 14.04 to 16.04 Upgrade failed

Solution 1:

This worked for me after a botched sudo do-release-upgrade from 14.04 to 16.04. The updater's automatic attempt to restore to the previous version failed as well but left me at the terminal where I was able to complete the upgrade as follows.

1) Replace the contents of /etc/apt/sources.list with the following

###### Ubuntu Main Repos
deb http://us.archive.ubuntu.com/ubuntu/ xenial main universe 
deb-src http://us.archive.ubuntu.com/ubuntu/ xenial main universe 

###### Ubuntu Update Repos
deb http://us.archive.ubuntu.com/ubuntu/ xenial-security main universe 
deb http://us.archive.ubuntu.com/ubuntu/ xenial-updates main universe 
deb-src http://us.archive.ubuntu.com/ubuntu/ xenial-security main universe 
deb-src http://us.archive.ubuntu.com/ubuntu/ xenial-updates main universe

Optional) If you are receiving error insserv: Service mountdevsubfs has to be enabled to start service hwclock1, run the command sudo rm /var/lib/dpkg/info/util-linux.postinst

2) sudo apt-get update -- updates package lists

3) sudo apt-get dist-upgrade -- this will take a while, installs all the updated packages

4) sudo apt-get autoremove -- removes unnecessary packages

5) sudo apt-get autoclean -- cleans old packages from repository

6) sudo update-grub -- updates grub boot config

Now if you run sudo do-release-upgrade, you should get the response No new release found. and you can reboot with sudo shutdown -r now. After reboot, you might want to repeat steps 2 to 5 to be sure all updates are installed.

Solution 2:

From the Official Ubuntu website: 14.04 LTS to LTS upgrades will be enabled with the 16.04.1 LTS point release, in approximately 3 months time.

If in a hurry, do a fresh install ;-)

Solution 3:

I think I fixed the error.

I reinstalled unity and ubuntu-desktop. I also had to enable desktop icons again (Ubuntu Tweak -> Tweaks -> Desktop Icons -> On). Everything looks normal again.