Check to see if the file '/var/lib/ubuntu-release-upgrader/release-upgrade-available' exists. If so you can remove it with no harm. However, it'd be interesting to know if running '/usr/lib/ubuntu-release-upgrader/release-upgrade-motd' removes the release-upgrade-available file.
Check to see if the file '/var/lib/ ubuntu- release- upgrader/ release- upgrade- available' exists. If so you can remove it with no harm. However, it'd be interesting to know if running '/usr/lib/ ubuntu- release- upgrader/ release- upgrade- motd' removes the release- upgrade- available file.