Downgrade to genuine version, using ppa-purge script, then also deactivate the other possible ppas. And run 'gtkorphan' & 'bleachbit' (as root, carefully select options) to clean the system. Next step is to reboot; at that point the dist-upgrade script should be able to set bionic as expected.
** 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/1769576 Title: not able to upgrade from ubuntu 16.04 to 18 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1769576/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs