Debian Bookworm: Testing the upcoming Debian release

Debian 12 Bookworm is expected to be released this summer. We want to give you a brief preview and info how to test it, either using our DietPi Bookworm images, or by upgrading your running DietPi Bullseye system.

Debian Bookworm theme background and Toy Story character
  1. Feature preview
    1.1 Release schedule
    1.2 Available software updates
    1.3 Other notable changes
  2. Current status
    2.1 Debian side
    2.2 DietPi side
  3. How to test
    3.1. DietPi Bookworm images
    3.2. Upgrade from Bullseye
  4. Giving feedback

Feature preview

1.1 Release schedule

Debian does not follow the rolling release model, but is a point release distribution, which provides updates for its distributed software via major releases every two years. The following table gives an overview of the last, current and next stable Debian release:

VersionCode nameCurrent statusRelease dateEnd-of-life (LTS)
10Busteroldstable2019-072022-09 (2024-06)
11Bullseyestable2021-082024-07 (2026-06)
12Bookwormtesting2023-08*2026-07 (2028-06)*
Debian release schedule:

During these two years, a stable Debian release receives only bug fixes, security patches and in rare cases patch version updates, i.e. updates where the upstream software developer does not declare any breaking changes or new features. You can observe this behaviour by looking at the version strings when doing apt upgrade: Usually only the suffix changes, indicating that the same software source code version was used. Changes were then limited to the package maintainer/meta files, including bug fix and security patches.
There are some exceptions for this strict update policy, like the Chromium browser, which receives regular major version upgrades for security reasons.

This means that at the end of a version release cycle, software provided by the Debian package repository is up to two years old and the next release hence provides some significant updates.

1.2 Available software updates

The following list shows an excerpt of updates available with Debian Bookworm for software often used on DietPi systems:

OpenSSH8.49.2adds full Ed25519 support, disables ssh-rsa support by default
Python3.93.11Not all Python applications have been tested by us with Python 3.11 yet.
PHP7.48.2Not all PHP applications have been tested by us with PHP 8.2 yet.
PostgreSQL1315The required database migration is included with our Bookworm upgrade script.
Kodi19.120.0not relevant for Raspberry Pi
Mesa graphics drivers20.3.522.3.3
Linux5.106.1relevant for x86_64 platforms only
Debian package versions derived from online database:

Notable are the PHP and Python upgrades to their respective latest official version, which affects a large number of dietpi-software installation options:

  • Some applications did already drop support for PHP 7.4 respectively Python 3.9, including Nextcloud and TasmoAdmin, which forces us do install older versions on Bullseye systems.
  • Other applications do not support PHP 8.2 respectively Python 3.11 yet and hence fail to run or install on Bookworm. ownCloud is an example, further explained below.

1.3 Other notable changes

There are some other changes we want to highlight:

Already since Linux 4.15, the kernel is able to obtain permitted WiFi channels/frequencies, the so called regulatory domains, from the regulatory database, based on a given WiFi country code. Previously, a dedicated user-space tool was needed to pass this information to the kernel: the Central Regulatory Domain Agent (CRDA). Since Debian Bullseye, the provided packages generally allows the use of this feature, and we hence offer the migration away from CRDA with the DietPi v8.14 upgrade. But on Bookworm, the CRDA package is not available at all. This means that systems, using a Linux version below 4.15, are not able to connect to a WiFi access point or provide one, using all locally allowed frequencies, but only a limited subset of shared global ones, which can break WiFi communication completely. This and a bunch of other uses of recent Linux kernel features force us to not provide Bookworm images for certain SBCs anymore, which have no Linux kernel of 4.15 or higher available.
This includes the Sparky SBC, NanoPi M2/T2/Fire2 and NanoPi M3/T3/Fire3 models. We are especially sad for the latter ones, which use a very powerful octa-core SoC, but the involved manufacturers have not managed to add support to mainline Linux or update their own kernel sources, stuck at Linux 4.4, which practically implies an artificially early end-of-life for such hardware.

Since Linux 5.15, an SMB kernel server ksmbd is available, similar to the NFS kernel server nfsd. This provides an alternative to the Samba user-space server, optimised for better performance and lower footprint running right in kernel-space. Debian Bookworm provides the needed user-space tools to manage this new SMB server implementation, and we are excited to implement it into dietpi-software as well.

2. Current status

2.1 Debian side

Debian Bookworm has not yet been released, and also the exact release date has not been decided yet. It is however expected to be this summer, most likely in August, like the last release Debian Bullseye.

As always, about half a year before the release, Debian starts a set of freeze stages, to incrementally settle the list of provided packages and their versions, first for fundamental libraries, toolchains and frameworks, backend software, over middleware, to frontend and end user software. At time of writing, the so called “soft freeze” has been reached. At 2023-03-12, the “hard freeze” will be reached. Details about the freeze stages can be found in the Debian website:

While during the first 1.5 years of a Debian testing phase, a lot of package upgrades with potentially breaking changes will be offered via APT, for Debian Bookworm in its current freeze stage, no big surprises are expected anymore, e.g. above listed software versions are not expected to change, and the number and frequency of package upgrades has become much lower. While it is still in testing, we can hence already recommend using Debian Bookworm in some production cases, e.g. when a newer PHP version is needed to run recent web applications. We use Debian Bookworm on the server already since a long time, and no manual setup change, config file update or similar intervention was needed recently.

2.2 DietPi side

DietPi offers Debian Bookworm based images since a long time, but we did not provide them prominently on our download page or elsewhere until now. However, general Bookworm support has been implemented shortly after the Bullseye release and since then we are testing our tools and software implementations on Bookworm systems as well, reacting to any breaking change. While quirks in special setups are possible, generally we can declare DietPi to be compatible with Debian Bookworm.

It is not complete or up-to-date in every case, but an overview of explicitly tested software titles can be found on our wiki:

The following list of software titles is known to be not (yet) compatible with Debian Bookworm:

Additionally, not all PHP and Python applications have been recently tested for PHP 8.2 and Python 3.11 support. You are invited to help testing the ones you need.

3. How to test

We made it very easy for you to test DietPi on Debian Bookworm, providing images as well as a script to upgrade your Debian Bullseye based DietPi system.

3.1 DietPi Bookworm images

While Bookworm images are not provided on our download page, your can find them for all devices (expect Sparky SBC, NanoPi M2/T2/Fire2 and NanoPi M3/T3/Fire3 as mentioned above) here:

Install them the same way you do with the current stable Bullseye images, e.g. by following our install instructions:

3.2 Upgrade from Bullseye

We wrote a script to upgrade a DietPi Bullseye system to Bookworm, as safe as possible. While flashing a fresh image is generally cleaner and recommended, we know that some of you have setups which are time consuming to replicate on a fresh system. Our script offers to create a backup, does all known needed migrations and adjustments to have your software running on the new Debian as it did before. Run the following one-liner on your console to execute it:

sudo bash -c "$(curl -sSf '')"

Carefully watch the output of the script. If an error occurs, our error handler allows you to open a subshell to investigate and fix the underlying issue, to repeat and continue. After the packages themselves have been upgraded, it allows you to again review the output, before continuing with software (config) migrations, which also includes some dietpi-software reinstalls.

4. Giving feedback

Feel free to use the comments for short feedback about this article and how Bookworm works for you.

For more detailed test results and issues you face with our upgrade script or Bookworm in general, please use the following issue on our GitHub repository:

Happy hacking!

Debian Bookworm: Testing the upcoming Debian release

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