I recently had to upgrade an Ubuntu 14.04 system to the latest release. I ran the command below and my system was upgraded to Ubuntu 16.04 LTS.
sudo do-release-upgrade |
This was run over SSH, but I did not lose my connection, and it was quite a painless experience. This is probably better than running sudo apt dist-upgrade. That also requires the editing of the /etc/apt/sources.list. But that can cause problems if there is an error. The sudo do-release-upgrade command is a better way to handle such a situation. Now I have a working Ubuntu 16.04 system with a new kernel. I just had to run sudo apt update and sudo apt upgrade to finish installing the flash plugin and a couple of other packages, and that was it.
Therefore, this is the best way to update a system, if you do not wish to re-install over the existing installation.