Question : The repository 'http://archive.ubuntu.com/ubuntu hirsute Release' no longer has a Release file.
Answered by : iheb-nachet
# backup your sources file
cp /etc/apt/sources.list /etc/apt/sources.list.bak
# replace the links with the archive address
sudo sed -i -re 's/([a-z]{2}.)?archive.ubuntu.com|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list
# run update again
sudo apt-get update && sudo apt-get dist-upgrade
Source : https://veducate.co.uk/ubuntu-apt-update-fails/ | Last Update : Mon, 02 May 22