I was trying to update a 12.04 to 12.10 and also got stuck by the no new release found issue. If one has no access to a GUI and wants the update on terminal, one has to edit
# Default prompting behavior, valid options:
# never - Never check for a new release.
# normal - Check to see if a new release is available. If more than one new
# release is found, the release upgrader will attempt to upgrade to
# the release that immediately succeeds the currently-running
# lts - Check to see if a new LTS release is available. The upgrader
# will attempt to upgrade to the first LTS release available after
# the currently-running one. Note that this option should not be
# used if the currently-running release is not itself an LTS
# release, since in that case the upgrader won't be able to
# determine if a newer release is available.
To test that the correct version is found, one can run
If that shows correct version, run:
sudo do-release-upgrade -d