If one wants to upgrade from 8.04 to 8.10 (server edition) one has to edit the file
/etc/update-manager/release-upgradesSearch for the string:
Prompt=ltsand change it to:
Prompt=normal(as described in the comments of the file). Now you should be able to run the upgrade utility:
sudo do-release-upgradeThis will start the upgrade process.
If you have followed previous hints on upgrade in this blog, you might have the upgrade-manager-core utility installed on your system (which includes do-release-upgrade). If not, you have to install it with sudo apt-get --install.
Upgrade takes approximately 20 mins on my server and requires a reboot to finalize the installation process.