Upgrade Debian 11 to Debian 12 Bookworm

This simple tutorial shows how to Upgrade Debian 11 to Debian 12 Bookworm. The Update process is divided in 8 simple steps.

1. Backup the system!

If you are using a VM or Container I would highly recommend to back up through the hypervisors UI, if you are on a local machine please also backup your entire machine!

2. Update existing packages and reboot the Debian 11 system

apt update
apt upgrade
apt full-upgrade
apt --purge autoremove

3. Edit sources.list

The easiest method is to replace bullseye with bookworm with the following command

sed -i -e 's/bullseye/bookworm/g' /etc/apt/sources.list

Also do the same for sources.list files in the folder /etc/apt/sources.list.d/

sed -i -e 's/bullseye/bookworm/g' /etc/apt/sources.list.d/*.*

4. Update the packages index on Debian Linux

apt update

5. Prepare for the operating system minimal system upgrade

apt upgrade --without-new-pkgs

6. Finally, update Debian 11 to Debian 12 Bookworm

apt full-upgrade

7. Reboot

reboot

8. Verify

lsb_release -a should show Release: 12 and debian_version should show 12.x

lsb_release -a

cat /etc/debian_version

The Upgrade Debian 11 to Debian 12 Bookworm is now completed.