xxxxxxxxxx
sudo sed -i -e 's/archive.ubuntu.com\|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list
**Linux Mint additionally requires the execution of this command:**
sudo sed -i -e 's/archive.ubuntu.com\|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list.d/official-package-repositories.list
xxxxxxxxxx
grep -E 'archive.ubuntu.com|security.ubuntu.com' /etc/apt/sources.list.d/*
xxxxxxxxxx
mkdir ~/solution
cd ~/solution/
cat << EOF > ~/solution/sources.list
deb http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
deb http://archive.canonical.com/ubuntu focal partner
deb-src http://archive.canonical.com/ubuntu focal partner
EOF
sudo sed -i "s/focal/$(lsb_release -c -s)/" ~/solution/sources.list
sudo rm /etc/apt/sources.list
sudo cp ~/solution/sources.list /etc/apt/sources.list