error apt update with ubuntu 21.04
## set git root@kube1-KVM:/home/kube1/Desktop# sudo sed -i -re 's/([a-z]{2}\.)?archive.ubuntu.com|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list root@kube1-KVM:/home/kube1/Desktop# sudo apt-get update && sudo apt-get dist-upgrade Get:1 http://old-releases.ubuntu.com/ubuntu impish InRelease [270 kB] Get:2 http://old-releases.ubuntu.com/ubuntu impish-updates InRelease [115 kB] Get:3 http://old-releases.ubuntu.com/ubuntu impish-backports InRelease [101 kB] Get:4 http://old-releases.ubuntu.com/ubuntu impish-security InRelease [110 kB] Get:5 http://old-releases.ubuntu.com/ubuntu impish/main amd64 Packages [1,396 kB] Get:6 http://old-releases.ubuntu.com/ubuntu impish/main i386 Packages [1,037 kB] Get:7 http://old-releases.ubuntu.com/ubuntu impish/main Translation-en [511 kB]