Upgrade Debian

December 13, 2025

Do a final upgrade of all packages.

apt update && apt upgrade && apt full-upgrade && apt autoremove

Back up sources.list and sources.list.d.

zip -r /root/apt-backup-$(date +%Y-%m-%d_%H:%M:%S)-sources.list.zip

Change the Debian flavor.

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

Do the thing.

apt update
apt upgrade
apt autoremove

Reboot, then we're done.