Debian 13 Upgrade: How to upgrade to Debian 13?

Upgrading to Debian 13 is an essential step in keeping your system up to date, secure and reliable. With the Trixie release, Debian introduces many improvements and updated software packages, suitable for both server and desktop environments. Updating from Debian 12 Bookworm takes just a few steps.

Step 1: Prepare the system

Before modifying your system, take the time to read the official Debian 13 (Trixie) release notes. They specify known issues, packages requiring special attention, and any restrictions that may affect your configuration. Start with the chapters dedicated to upgrade to Trixie and check if the programs you use are mentioned there. This step may seem trivial, but it often helps avoid major problems later.

Step 2: Create a Full Backup

Before upgrading to Debian 13, it is essential to back up your data. Although the update usually goes smoothly, a power outage, faulty disk, or packet conflict may prevent your system from restarting properly. Thanks to a prior backup, you will be able to restore your environment without loss of data. So it is crucial not only to create the backup, but also to verify that it works. After the backupmake sure all files are complete and accessible.

Back up directories at a minimum /etc (configurations), /home (user files), database exports (/var/lib/mysql Or mysqldump) as well as any web or application data. If you use a virtual machine (VM) or Cloud service, create a snapshot or full image. Also keep the output of the following command:

dpkg --get-selections '*'

The result displays a tabular list of all known packages on your system, along with their status. This information will be useful to restore packages after upgrading to Debian 13.

Step 3: Check the current status of your system

Before you start upgrading to Debian 13, make sure your system is running Debian 12, i.e. Bookworm. You can check it easily by showing Debian version with the following command:

cat /etc/debian_version

In the output, you should see “bookworm” or “12”. It is also important to check the available disk space. Upgrading to Debian 13 downloads many new packages which will be stored temporarily. If there is insufficient space, the operation may fail. Use the following command in the terminal to check if you have enough space :

apt -o APT::Get::Trivial-Only=true full-upgrade

If you receive the following warning message, your disk space is insufficient to upgrade to Debian 13. You should therefore free up space before continuing:

E: You don't have enough free space in /var/cache/apt/archives/.

Step 4: Update the existing system

Before upgrading from Debian 12 to Debian 13, make sure your current system is fully up to date. To do this, run the following commands:

sudo apt update
sudo apt upgrade -y
sudo apt full-upgrade -y
sudo apt autoremove --purge -y

This step is essential because it helps fix possible minor errors and security vulnerabilities, establishing a stable foundation for a clean upgrade. Only once your Bookworm system is fully up to date should you begin the transition to Trixie.

Step 5: Check retained packets

Sometimes some packets are placed on hold (hold). This means that they are not updated automatically, even when new versions are available. These packages can cause problems during the upgrade because they prevent the correct resolution of the dependencies. You can check easily if packets are currently waiting on your system using the following command:

If this is the case, you should release these packets To make the upgrade work smoothly:

sudo apt-mark unhold paketname

Step 6: Control External Package Sources

Over time, many users add additional package sources to their system, for example to install specific software that is not in the official Debian archive. These external sources are often the cause of problems when upgrading to Debian 13. It is therefore recommended to check your package source list :

apt list '?narrow(?installed, ?not(?origin(Debian)))'

Temporarily disable or remove all entries that do not belong to Debian. The safest method is to ensure your system only uses official packages of Debian during the update.

Step 7: Switch Package Sources to Debian 13

Once your system is prepared, it's time to change the package sources from Debian 12 to Debian 13. The sources can be found in the file /etc/apt/sources.list as well as, for certain entries, in the directory /etc/apt/sources.list.d/. Open these files in a text editor and replace each occurrence of the term « bookworm » with « trixie. » Be sure to edit all entries so that all packages are loaded from the new sources. Before continuing, it is recommended to save the old version of the file so that you can revert to it in the event of an error.

Step 8: Create a stable working environment

If you are upgrading on a remote server via SSH, there is still a risk of connection interruption during the process. In the worst case, this can result in an incomplete upgrade. To avoid this problem, use programs like screen Or tmux. These tools open a secondary session that continues to run in the backgroundeven in case of SSH disconnection. In our example, we use screen with the following commands:

sudo apt install screen -y
screen -S upgrade-session

Step 9: Initiate a minimal upgrade to Debian 13

Once the preparations are complete, start by performing a minimal upgrade. Only packages that can be replaced without causing major conflicts will then be updated. This intermediate step helps reduce the risk that an essential service suddenly stops functioning. Only after successfully completing this first phase can you proceed with the full upgrade. For start minimal upgrade To Debian 13, run the following command:

apt upgrade --without-new-pkgs

Step 10: Perform Full Upgrade

You can now start the full upgrade. This is the central stage in which your Debian system goes from version 12 to version 13. During this process, many packages are downloaded, unpacked and installed. The system may repeatedly ask you how to process certain configuration files. Generally, it is recommended to accept the proposed new version of the file. Run the following command to start upgrade to Debian 13:

Be patient! This step may take some time depending on the speed of your hardware and internet connection.

Step 11: Reboot with the new kernel

Upgrading to Trixie usually also includes a kernel update (kernel). It is strongly recommended to have a meta-package installed linux-image- * (For example linux-image-amd64 for an AMD64 architecture), so that future kernel updates* are installed automatically . Check the presence of a meta-package* using the following command:

dpkg -l 'linux-image*' | grep ^ii | grep -i meta

If there is no no meta-package presentyou can install one with the following command:

apt install linux-image-amd64

After a kernel update, a reboot is required for it to be fully operational. The release notes explicitly state that a reboot is required.

Step 12: finishing touches and cleaning

Even if the system works fine after rebooting, some cleanup still needs to be done. It is recommended to remove obsolete packages and dependencies to keep your system light and clean. To do this, use the command apt autoremove. Additionally, packages that become unnecessary after upgrading to Debian 13 should be removed from the system. You can view and delete them using the following commands:

apt list '?obsolete'
apt purge '?obsolete'

You no longer need obsolete package configuration files :

apt list '?config-files'
apt purge '?config-files'

Your system is now successfully updated to Debian 13 (Trixie) and can be used normally. For example, you can install database management systems such as PostgreSQL on Debian 13 or download other programs as usual.