Comment 13 for bug 2037738

This worked for me:

Change source.list to old-releases

sudo sed -i -re 's/([a-z]{2}.)?archive.ubuntu.com|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list

edit the sources.list file (using admin rights by sudo) and put a comment indicator ('#') to the beginning of the lines that contain "kinetic-updates".

Then run
sudo apt update

and re-try

sudo do-release-upgrade