Upgrade Debian 12 to Debian 13 – the complete administrator checklist

Debian 13 “Trixie” is the current stable release. Debian 13.6 was released on July 11, 2026, while Debian 12 is now in its LTS phase. A Bookworm upgrade should be treated as a controlled migration, not a casual `apt upgrade`.

Build an inventory first

Record installed packages, third-party repositories, Docker, PHP, MariaDB, Apache/Nginx, systemd services, cron jobs, certificates, mounts and firewall rules.

Back up before upgrading

Back up configurations, databases and important data, and make sure there is a real recovery path.

Third-party repositories

Disable or verify external repositories before the release upgrade. Re-enable them only after confirming Trixie support.

PHP and web servers

Check PHP modules, Composer dependencies, Apache/Nginx configuration and permissions.

Docker

Before upgrading, record `docker --version`, `docker compose version` and `docker-compose --version`. Old automation may fail afterwards.

docker --version
docker compose version
docker-compose --version

MariaDB and PostgreSQL

Take logical backups and record versions. After the upgrade, test both database services and applications.

Do not forget SSH

If the server is remote, SSH is your lifeline. Check configuration, keys, firewall rules and maintain a second working access path.

The actual upgrade

Update the existing system, carefully change Bookworm sources to Trixie, refresh package lists, perform the full upgrade and reboot. The official release notes remain the authoritative reference.

After reboot

Check failed units, networking, DNS, SSH, Docker, web servers, databases, mounts and certificates.

Conclusion

A Debian upgrade is a controlled migration, not one command. Inventory, backups and post-upgrade service checks reduce risk dramatically.