Upgrade from Debian 11 Bullseye to Debian 12 Bookworm#

Expect the upgrade to take about 20–30 minutes, mostly waiting for packages to download.

Update APT sources#

sudo nano /etc/apt/sources.list

Change every line that has:

bullseye main contrib non-free

to:

bookworm main contrib non-free non-free-firmware

Do this for all deb and deb-src lines. For example: deb http://deb.debian.org/debian/ bookworm main contrib non-free non-free-firmware

sudo apt update

sudo apt upgrade --without-new-pkgs

sudo apt full-ugrade

sudo apt autoremove

Reboot:

sudo reboot

Verify:

cat /etc/os-release

You should see PRETTY_NAME="Debian GNU/Linux 12 (bookworm)".