Upgrade from Debian 12 to Debian 13

Debian's major version upgrade process is very reliable, but still requires careful operation. This document will guide you through a smooth upgrade from Debian 12 "Bookworm" to Debian 13 "Trixie".

Read before upgrading

• Be sure to back up important data (at least /home and /etc).
• Perform the upgrade in a stable network and power environment; for laptops, connect to power.
• It is recommended to read the entire document before starting. If it is a production server, test it in a staging environment first.

Step 1: Fully update the current system

First, update your existing Debian 12 to the latest state to reduce conflicts during the upgrade:

sudo apt update
sudo apt upgrade --without-new-pkgs
sudo apt full-upgrade
sudo apt autoremove

Verify that you are currently on Debian 12:

lsb_release -a
# Should show Release: 12, Codename: bookworm

Step 2: Check and record installed third-party repositories

Third-party repositories (such as Docker, Chrome repos) may be incompatible with major version upgrades. It is recommended to temporarily disable them, and restore them one by one after the upgrade:

# List all repository files
ls /etc/apt/sources.list.d/

You can temporarily move away third-party .list / .sources files, keeping only the official Debian repositories for the upgrade.

Step 3: Change the software sources to trixie

This is the core step of the upgrade — change the distribution codename from bookworm to trixie.

If you use the traditional sources.list:

sudo sed -i 's/bookworm/trixie/g' /etc/apt/sources.list

If you use the deb822 format (Debian 12 may also use /etc/apt/sources.list.d/debian.sources):

sudo sed -i 's/bookworm/trixie/g' /etc/apt/sources.list.d/debian.sources

Note the change in security suite names

Old security sources are named bookworm-security, the new ones correspond to trixie-security. The replacement above will handle both. Please open the file to confirm that all bookworm* have become trixie*.

Don't forget to check other official repository files under /etc/apt/sources.list.d/ and replace them as well.

Step 4: Perform the upgrade

# 1. Refresh the package list with the new trixie sources
sudo apt update

# 2. Minimal upgrade (upgrade core packages first, lower risk of conflicts)
sudo apt upgrade --without-new-pkgs

# 3. Full upgrade (install new kernel, handle dependency changes, install new packages)
sudo apt full-upgrade

The full upgrade will download a large number of files and take a long time. During this process, configuration file conflict prompts may appear. It is generally safe to choose "install the package maintainer's version" (unless you have actually manually modified that configuration).

Step 5: Reboot and verify

sudo reboot

Verify after reboot:

lsb_release -a
# Should show Release: 13, Codename: trixie

uname -r
# The kernel should be version 6.12 series

Step 6: Post-upgrade cleanup and finalization

# Clean up old packages left over from the upgrade
sudo apt autoremove --purge

# Optional: Migrate sources to Debian 13's default deb822 format
sudo apt modernize-sources

Then restore previously disabled third-party repositories one by one, and confirm they provide trixie (or compatible) versions. See deb822 source format for more details on deb822.

Common issues

• Upgrade interrupted / network lost: After restoring the network, rerun sudo apt full-upgrade; APT will continue where it left off.
• Some packages are "kept back": Running sudo apt full-upgrade usually resolves this.
• Skipping multiple major versions (e.g., from Debian 11): Do not skip versions; you should first upgrade to Debian 12, then to Debian 13.

Summary

1. Update the current system → 2. Handle third-party repositories → 3. Change source codename bookworm→trixie → 4. update + upgrade + full-upgrade → 5. Reboot and verify → 6. Clean up and migrate to deb822.

Further reading: deb822 source format · APT package management