I’ve been upgrading my Debian 12 (bookworm) server fleet to Debian 13 (trixie).
Here is the successful process I ended up following for them all.
The process is essentially: update your package lists, switch the repository URLs from bookworm to trixie, and run the upgrade. Here is how I did it.
Step 1: Make sure your current system is fully up to date
Before switching repositories, bring your Debian 12 install to the latest patch level:
apt update
apt full-upgrade
apt autoremove
apt autoclean
Reboot afterwards so you are running the latest kernel before the upgrade:
reboot
Step 2: Backup your apt configuration
Good practice before changing anything:
cp -a /etc/apt /etc/apt.bak.$(date +%F)
If something goes wrong, you can restore the entire apt configuration from the backup.
Step 3: Switch repositories from bookworm to trixie
This is the core of the upgrade. Replace every occurrence of “bookworm” with “trixie” in your apt sources:
sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
For any additional files in sources.list.d, handle them the same way:
find /etc/apt/sources.list.d -type f \( -name '*.list' -o -name '*.sources' \) -exec sed -i 's/bookworm/trixie/g' {} \;
Step 4: Update package lists
apt update
You will likely see key warnings at this point as you don’t have the latest keys yet.
Step 5: Refresh the keyring
apt install debian-archive-keyring
apt update
This installs the updated signing keys for the trixie repositories and clears the warnings.
Step 6: Perform the upgrade
I used a two-phase approach which is somewhat safer.
Phase 1: Upgrade existing packages without pulling in new dependencies:
apt upgrade --without-new-pkgs
Phase 2: Full upgrade — installs new packages, removes obsolete ones, and completes the distribution upgrade:
apt full-upgrade
This will take a while depending on your system and internet connection. Let it run.
Step 7: Cleanup
apt autoremove
apt autoclean
Step 8: Reboot
reboot
The kernel and systemd will have been upgraded, so a reboot is required.
Step 9: Verify
cat /etc/os-release
cat /etc/debian_version
You should see “Debian GNU/Linux 13 (trixie)” or similar. If you prefer the classic lsb_release output:
apt install lsb-release -y
lsb_release -a
Notes
If you are using a desktop environment or have third-party repositories (Docker, PostgreSQL, etc.), check that they have trixie-compatible entries in sources.list.d after the switch and, in case, update them accordingly.
As always, make sure you have a recent backup before upgrading a production system.
I hope you find this useful!