I had to keep using 19.04 for a while after it was discontinued for a variety of reasons. I would now like to move up in the world to 20.04. I have tried following a number of paths, for example the sequence of steps which is described here: https://www.reddit.com/r/Lubuntu/comments/g3390k/1904_the_repository_standard_repo_no_longer_has_a/
In brief, this means, eg:
sudo sed -i 's/disco/focal/g' /etc/apt/sources.list
sudo apt update && sudo apt full-upgrade
The error message I get, which seems to be reproduced across the internet, is as follows:
E: The repository 'http://ppa.launchpad.net/deadsnakes/ppa/ubuntu disco Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
N: Skipping acquire of configured file 'universe/binary-i386/Packages' as repository 'http://miktex.org/download/ubuntu xenial InRelease' doesn't support architecture 'i386'
E: The repository 'http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu disco Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
I guess it's been long enough now though that somebody somewhere must have found a fix to this, no? Does anybody know what to do?
Thanks!