Upgrade from 13.10 to 14.04: "No new release found"

For me the reason was that I had disabled the automatic checking for upgrades, as the check-new-release process kept significantly slowing down my computer.

Changing back to Prompt=normal in /etc/update-manager/release-upgrades instantly fixed the problem.

It finally worked. The problem was that I did do-release-upgrade as root, this didn't work. Invoking this command as normal user worked. Hower I don't understand why it doesn't as root.

Try This!!!

Cut and paste entire set of below commands :

sudo apt-get clean ;
cd /var/lib/apt ;
sudo mv lists lists.old_`date '+%Y%m%d_%H%M%S'`   ;
sudo mkdir -p lists/partial ;
sudo apt-get clean ;
sudo apt-get update

The semicolon demarcates each command so they can be pasted together. After that do this:

sudo apt-get clean
sudo do apt-get update
sudo apt-get dist-upgrade  
sudo do-release-upgrade

If that fails, then do this:

sudo sed -i 's/saucy/trusty/g' /etc/apt/sources.list
sudo apt-get update
sudo apt-get upgrade 

Note: Remove All third party PPAs unless they have an 14.04 version available. If you have the Gnome PPA remove it with PPA-Purge.