doc/releases/index.rst - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 .. _zephyr_release_notes:

 Releases
 ########

 Zephyr project is provided as source code and build scripts for different target
 architectures and configurations, and not as a binary image. Updated versions of
 the Zephyr project are released approximately every six months.

 All Zephyr project source code is maintained in a `GitHub repository`_. In order
 to use a released version of the Zephyr project, it is recommended that you use
 :ref:`west` to :ref:`get_the_code` of the release you are interested in.

 The technical documentation for current and past releases is available at
 https://docs.zephyrproject.org/ (use the version selector to select your release
 of interest).

 .. _zephyr_release_cycle:

 Release Life Cycle and Maintenance
 **********************************

 Major and Maintenance Release Cadence
 =====================================

 The Zephyr Project delivers major releases using a six month cadence roughly timed
 each April and October of the year.

 This timescale facilitates regular releases that have strong QA cycles while
 not overwhelming users with too many new releases.

 The cadence is predictable and avoids many major holidays in various geographies.

 The Zephyr project delivers maintenance releases on an unscheduled basis and
 are usually driven by the accumulation of enough significant fixes or enhancements
 to the associated major release.

 The point release indicates a point in the major release branch where a full QA
 cycle and release process validates the content of the new branch.

 Long Term Support and Maintenance
 =================================

 While stable releases are supported for the duration of 2 release cycles (roughly 1 year),
 some specific ones will be supported for a longer period by the Zephyr Project,
 and are called Long Term Support (LTS) releases.

 A Zephyr :ref:`Long Term Support (LTS) <release_process_lts>` release is
 published every 2.5 to 3 years and is branched and maintained independently from the
 main tree for approximately 5 years after it was released.

 This offers more stability to project users and leaves more time to
 upgrade to the following LTS release.


 Transitioning to the new Release Cadence
 ========================================

 The transition to the new release cadence will begin in 2026. Zephyr 4.4 is scheduled
 for release in April 2026, and subsequent releases will occur every six months.

 The projected timeline for upcoming releases is as follows:

 +---------+-------------------+---------------------+
 | Release | Planned Date      | Notes               |
 +=========+===================+=====================+
 | 4.4     | April 2026        |                     |
 +---------+-------------------+---------------------+
 | 4.5     | October 2026      |                     |
 +---------+-------------------+---------------------+
 | 4.6     | April 2027        | LTS4                |
 +---------+-------------------+---------------------+
 | 5.0     | October 2027      | Start of 5.x cycle  |
 +---------+-------------------+---------------------+
 | 5.1     | April 2028        |                     |
 +---------+-------------------+---------------------+
 | 5.2     | October 2028      |                     |
 +---------+-------------------+---------------------+
 | 5.3     | April 2029        |                     |
 +---------+-------------------+---------------------+
 | 5.4     | October 2029      | LTS5                |
 +---------+-------------------+---------------------+

 Starting with the 5.x release cycle, all releases will follow the new six-month
 cadence from the beginning.


 Security Fixes
 ==============

 Each security issue fixed within Zephyr is backported or submitted to the
 following releases:

 - Currently supported Long Term Support (LTS) release.

 - The most recent two releases.

 For more information, see  :ref:`Security Vulnerability Reporting <reporting>`.

 .. _supported_releases:

 Supported Releases
 ******************

 +------------------------+----------------+---------------+
 | Release                | Release date   | EOL           |
 +========================+================+===============+
 | `Zephyr 4.2.0`_        | 2025-07-18     | 2026-03-20    |
 +------------------------+----------------+---------------+
 | `Zephyr 4.1.0`_        | 2025-03-07     | 2025-11-14    |
 +------------------------+----------------+---------------+
 | `Zephyr 3.7.0 (LTS3)`_ | 2024-07-26     | 2029-07-27    |
 +------------------------+----------------+---------------+

 Previous LTS
 ************

 +-------------------------+---------------+
 | Release                 | EOL           |
 +=========================+===============+
 | `Zephyr 2.7.6 (LTS2)`_  | 2025-01-26    |
 +-------------------------+---------------+
 | `Zephyr 1.14.1 (LTS1)`_ | 2022-01-01    |
 +-------------------------+---------------+

 Release Notes
 *************

 Release notes contain a list of changes that have been made to the different
 areas of the project during the development cycle of the release.
 Changes that require the user to modify their own application to support the new
 release may be mentioned in the release notes, but the details regarding *what*
 needs to be changed are to be detailed in the release's migration guide.

 Updates to the release notes post release cycle is permitted but limited to
 style, typographical fixes and to upmerge the notes from maintenance release
 branches with the sole purpose of keeping the latest documentation consistent
 with the changes in the project.

 .. toctree::
    :maxdepth: 1
    :glob:
    :reversed:

    release-notes-3.7
    release-notes-4.[1-3]

 Migration Guides
 ****************

 Zephyr provides migration guides for all major releases, in order to assist
 users transition from the previous release.

 As mentioned in the previous section, changes in the code that require an action
 (i.e. a modification of the source code or configuration files) on the part of
 the user in order to keep the existing behavior of their application belong in
 in the migration guide. This includes:

 - Breaking API changes
 - Deprecations
 - Devicetree or Kconfig changes that affect the user (changes to defaults,
   renames, etc)
 - Treewide changes that have an effect (e.g. changing the include path or
   defaulting to a different C standard library)
 - Anything else that can affect the compilation or runtime behavior of an
   existing application

 Each entry in the migration guide must include a brief explanation of the change
 as well as refer to the Pull Request that introduced it, in order for the user
 to be able to understand the context of the change.

 .. toctree::
    :maxdepth: 1
    :glob:
    :reversed:

    migration-guide-3.7
    migration-guide-4.[1-3]

 End-of-life Releases
 ********************

 .. toctree::
    :hidden:
    :maxdepth: 1

    eol_releases

 Release notes and migration guides for end-of-life releases of Zephyr RTOS can be accessed
 :ref:`here <eol_releases>`.

 .. _`GitHub repository`: https://github.com/zephyrproject-rtos/zephyr
 .. _`GitHub tagged releases`: https://github.com/zephyrproject-rtos/zephyr/tags
 .. _`Zephyr 1.14.1 (LTS1)`: https://docs.zephyrproject.org/1.14.1/
 .. _`Zephyr 2.7.6 (LTS2)`: https://docs.zephyrproject.org/2.7.6/
 .. _`Zephyr 3.7.0 (LTS3)`: https://docs.zephyrproject.org/3.7.0/
 .. _`Zephyr 4.1.0`: https://docs.zephyrproject.org/4.1.0/
 .. _`Zephyr 4.2.0`: https://docs.zephyrproject.org/4.2.0/
	.. _zephyr_release_notes:

	Releases
	########

	Zephyr project is provided as source code and build scripts for different target
	architectures and configurations, and not as a binary image. Updated versions of
	the Zephyr project are released approximately every six months.

	All Zephyr project source code is maintained in a `GitHub repository`_. In order
	to use a released version of the Zephyr project, it is recommended that you use
	:ref:`west` to :ref:`get_the_code` of the release you are interested in.

	The technical documentation for current and past releases is available at
	https://docs.zephyrproject.org/ (use the version selector to select your release
	of interest).

	.. _zephyr_release_cycle:

	Release Life Cycle and Maintenance
	**********************************

	Major and Maintenance Release Cadence
	=====================================

	The Zephyr Project delivers major releases using a six month cadence roughly timed
	each April and October of the year.

	This timescale facilitates regular releases that have strong QA cycles while
	not overwhelming users with too many new releases.

	The cadence is predictable and avoids many major holidays in various geographies.

	The Zephyr project delivers maintenance releases on an unscheduled basis and
	are usually driven by the accumulation of enough significant fixes or enhancements
	to the associated major release.

	The point release indicates a point in the major release branch where a full QA
	cycle and release process validates the content of the new branch.

	Long Term Support and Maintenance
	=================================

	While stable releases are supported for the duration of 2 release cycles (roughly 1 year),
	some specific ones will be supported for a longer period by the Zephyr Project,
	and are called Long Term Support (LTS) releases.

	A Zephyr :ref:`Long Term Support (LTS) <release_process_lts>` release is
	published every 2.5 to 3 years and is branched and maintained independently from the
	main tree for approximately 5 years after it was released.

	This offers more stability to project users and leaves more time to
	upgrade to the following LTS release.


	Transitioning to the new Release Cadence
	========================================

	The transition to the new release cadence will begin in 2026. Zephyr 4.4 is scheduled
	for release in April 2026, and subsequent releases will occur every six months.

	The projected timeline for upcoming releases is as follows:

	+---------+-------------------+---------------------+
	\| Release \| Planned Date \| Notes \|
	+=========+===================+=====================+
	\| 4.4 \| April 2026 \| \|
	+---------+-------------------+---------------------+
	\| 4.5 \| October 2026 \| \|
	+---------+-------------------+---------------------+
	\| 4.6 \| April 2027 \| LTS4 \|
	+---------+-------------------+---------------------+
	\| 5.0 \| October 2027 \| Start of 5.x cycle \|
	+---------+-------------------+---------------------+
	\| 5.1 \| April 2028 \| \|
	+---------+-------------------+---------------------+
	\| 5.2 \| October 2028 \| \|
	+---------+-------------------+---------------------+
	\| 5.3 \| April 2029 \| \|
	+---------+-------------------+---------------------+
	\| 5.4 \| October 2029 \| LTS5 \|
	+---------+-------------------+---------------------+

	Starting with the 5.x release cycle, all releases will follow the new six-month
	cadence from the beginning.


	Security Fixes
	==============

	Each security issue fixed within Zephyr is backported or submitted to the
	following releases:

	- Currently supported Long Term Support (LTS) release.

	- The most recent two releases.

	For more information, see :ref:`Security Vulnerability Reporting <reporting>`.

	.. _supported_releases:

	Supported Releases
	******************

	+------------------------+----------------+---------------+
	\| Release \| Release date \| EOL \|
	+========================+================+===============+
	\| `Zephyr 4.2.0`_ \| 2025-07-18 \| 2026-03-20 \|
	+------------------------+----------------+---------------+
	\| `Zephyr 4.1.0`_ \| 2025-03-07 \| 2025-11-14 \|
	+------------------------+----------------+---------------+
	\| `Zephyr 3.7.0 (LTS3)`_ \| 2024-07-26 \| 2029-07-27 \|
	+------------------------+----------------+---------------+

	Previous LTS
	************

	+-------------------------+---------------+
	\| Release \| EOL \|
	+=========================+===============+
	\| `Zephyr 2.7.6 (LTS2)`_ \| 2025-01-26 \|
	+-------------------------+---------------+
	\| `Zephyr 1.14.1 (LTS1)`_ \| 2022-01-01 \|
	+-------------------------+---------------+

	Release Notes
	*************

	Release notes contain a list of changes that have been made to the different
	areas of the project during the development cycle of the release.
	Changes that require the user to modify their own application to support the new
	release may be mentioned in the release notes, but the details regarding what
	needs to be changed are to be detailed in the release's migration guide.

	Updates to the release notes post release cycle is permitted but limited to
	style, typographical fixes and to upmerge the notes from maintenance release
	branches with the sole purpose of keeping the latest documentation consistent
	with the changes in the project.

	.. toctree::
	:maxdepth: 1
	:glob:
	:reversed:

	release-notes-3.7
	release-notes-4.[1-3]

	Migration Guides
	****************

	Zephyr provides migration guides for all major releases, in order to assist
	users transition from the previous release.

	As mentioned in the previous section, changes in the code that require an action
	(i.e. a modification of the source code or configuration files) on the part of
	the user in order to keep the existing behavior of their application belong in
	in the migration guide. This includes:

	- Breaking API changes
	- Deprecations
	- Devicetree or Kconfig changes that affect the user (changes to defaults,
	renames, etc)
	- Treewide changes that have an effect (e.g. changing the include path or
	defaulting to a different C standard library)
	- Anything else that can affect the compilation or runtime behavior of an
	existing application

	Each entry in the migration guide must include a brief explanation of the change
	as well as refer to the Pull Request that introduced it, in order for the user
	to be able to understand the context of the change.

	.. toctree::
	:maxdepth: 1
	:glob:
	:reversed:

	migration-guide-3.7
	migration-guide-4.[1-3]

	End-of-life Releases
	********************

	.. toctree::
	:hidden:
	:maxdepth: 1

	eol_releases

	Release notes and migration guides for end-of-life releases of Zephyr RTOS can be accessed
	:ref:`here <eol_releases>`.

	.. _`GitHub repository`: https://github.com/zephyrproject-rtos/zephyr
	.. _`GitHub tagged releases`: https://github.com/zephyrproject-rtos/zephyr/tags
	.. _`Zephyr 1.14.1 (LTS1)`: https://docs.zephyrproject.org/1.14.1/
	.. _`Zephyr 2.7.6 (LTS2)`: https://docs.zephyrproject.org/2.7.6/
	.. _`Zephyr 3.7.0 (LTS3)`: https://docs.zephyrproject.org/3.7.0/
	.. _`Zephyr 4.1.0`: https://docs.zephyrproject.org/4.1.0/
	.. _`Zephyr 4.2.0`: https://docs.zephyrproject.org/4.2.0/