What release / version are you running?
But you knew that already — to upgrade the version of the Ubuntu installation you have is quite simple – just storing it so that I have it somewhere 🙂
sudo apt-get install update-manager-core sudo do-release-upgrade
And you’re done! Just give it time (about 1 hr on a slow [54kB/s] connection) ! When running it via SSH, a secondary SSH port is opened for you to allow for external remote access should your current SSH session is reset / crashes / fails…
Wash, rinse and repeat!