Upgrade debian 10 to debian 11
Pre-Requisites
Backup the whole system!
Update System
sudo apt update && sudo apt upgrade
Replace Repo With Debian 11
cp /etc/apt/sources.list /etc/apt/sources.list.bak
cat << EOF >/etc/apt/sources.list
deb http://deb.debian.org/debian/ bullseye main contrib non-free
deb-src http://deb.debian.org/debian/ bullseye-updates main contrib non-free
deb http://security.debian.org/debian-security bullseye-security main
deb-src http://security.debian.org/debian-security bullseye-security main
deb http://ftp.debian.org/debian bullseye-backports main contrib non-free
EOF
Upgrade the System to Debian 11
sudo apt update
sudo apt full-upgrade
Restart and Confirm OS Version
sudo reboot
cat /etc/os-release
Purge outdated package
sudo apt --purge autoremove