I'm guessing, as its not clear from your description, that your issue is about not being able to upgrade from Ubuntu 17.10 to Ubuntu 18.04. If your issue is about an upgrade failure it would help to have the file /var/log/dist-upgrade/main.log. Without it I'd make another guess that this is because you have installed ROS packages from their PPA. If both my guesses are right you'll want to purge the PPA using the package and tool ppa-purge to remove it and install official versions of any packages they provide.
** Changed in: ubuntu-release-upgrader (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1781409 Title: the newer version of ubuntu is not getting updated To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1781409/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs