That's an unsupported upgrade method. Please issue "update-manager -d" in a desktop install, or "do-release-upgrade -d" on a server or other command line environment.
And before people complain about the command line, this is possible in the GUI as well.
System - Administration - Update Manager
Click "Settings"
Under "Updates" select "Show new distribution releases: Normal releases"
By default if you are running an LTS release, Update Manager assumes you want to update only to the next LTS release. This setting will cause it to prompt you to update to the next non-LTS release and each other from then on.
