Upgrade Your KDE neon install to Bionic rebase
Due to the nature of software distribution on Linux, upgrade scenarios are hugely complicated. We have automated QA measures in place to ensure our software upgrades correctly. Any piece of non-KDE software can cause the upgrade to fail without us being able to do much about it though. So, if you have lots of non-KDE software installed, especially from third party PPAs, you should be ready to have the upgrade go wrong and potentially end up with a broken system. We suggest that you do a clean installation using the ISOs and restore your data from a back up, if that happens. Using third party software as AppImages, Flatpaks or Snaps largely eliminates this problem; something to keep in mind for the future.
Make sure that you have your important data backed up before attempting an upgrade!