[ubuntu] "Repository does not have a release file" error

#For Unable to 'apt update' my Ubuntu 19.04

The repositories for older releases that are not supported (like 11.04, 11.10 and 13.04) get moved to an archive server. There are repositories available at http://old-releases.ubuntu.com.

first break up this file

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

then

sudo apt-get update && sudo apt-get dist-upgrade