1.. _zephyr_release_notes:
2
3Releases
4########
5
6Zephyr project is provided as source code and build scripts for different target
7architectures and configurations, and not as a binary image. Updated versions of
8the Zephyr project are released approximately every four months.
9
10All Zephyr project source code is maintained in a `GitHub repository`_. In order
11to use a released version of the Zephyr project, it is recommended that you use
12:ref:`west` to :ref:`get_the_code` of the release you are interested in.
13
14The technical documentation for current and past releases is available at
15https://docs.zephyrproject.org/ (use the version selector to select your release
16of interest).
17
18Release Life Cycle and Maintenance
19**********************************
20
21Periodic Releases
22=================
23
24The Zephyr project provides periodic releases every 4 months leading to the
25long term support releases approximately every 2 years. Periodic and non-LTS
26releases are maintained with updates, bug fixes and security related updates
27for at least two cycles, meaning that the project supports the most recent two
28releases in addition to the most recent LTS.
29
30Long Term Support and Maintenance
31=================================
32
33A Zephyr :ref:`Long Term Support (LTS) <release_process_lts>` release is
34published every 2 years and is branched and maintained independently from the
35main tree for at least 2.5 years after it was released.
36
37Support and maintenance for an LTS release stops at least half a year
38after the following LTS release is published.
39
40Security Fixes
41==============
42
43Each security issue fixed within Zephyr is backported or submitted to the
44following releases:
45
46- Currently supported Long Term Support (LTS) release.
47
48- The most recent two releases.
49
50For more information, see  :ref:`Security Vulnerability Reporting <reporting>`.
51
52
53Supported Releases
54******************
55
56+-----------------+----------------+---------------+
57| Release         | Release date   | EOL           |
58+=================+================+===============+
59| `Zephyr 2.7.5`_ | 2023-06-01     | 2024-08-31    |
60+-----------------+----------------+---------------+
61| `Zephyr 3.6.0`_ | 2024-02-23     | 2024-11-29    |
62+-----------------+----------------+---------------+
63| `Zephyr 3.5.0`_ | 2023-10-20     | 2024-07-26    |
64+-----------------+----------------+---------------+
65
66As of 2022-01-01, LTS1 (1.14.x) is not supported and has reached end of life (EOL).
67
68Release Notes
69*************
70
71Release notes contain a list of changes that have been made to the different
72areas of the project during the development cycle of the release.
73Changes that require the user to modify their own application to support the new
74release may be mentioned in the release notes, but the details regarding `what`
75needs to be changed are to be detailed in the release's migration guide.
76
77.. toctree::
78   :maxdepth: 1
79   :glob:
80   :reversed:
81
82   eol_releases
83   release-notes-2.7
84   release-notes-3.[5-6]
85
86Migration Guides
87****************
88
89Zephyr provides migration guides for all major releases, in order to assist
90users transition from the previous release.
91
92As mentioned in the previous section, changes in the code that require an action
93(i.e. a modification of the source code or configuration files) on the part of
94the user in order to keep the existing behavior of their application belong in
95in the migration guide. This includes:
96
97- Breaking API changes
98- Deprecations
99- Devicetree or Kconfig changes that affect the user (changes to defaults,
100  renames, etc)
101- Treewide changes that have an effect (e.g. changing the include path or
102  defaulting to a different C standard library)
103- Anything else that can affect the compilation or runtime behavior of an
104  existing application
105
106.. toctree::
107   :maxdepth: 1
108   :glob:
109   :reversed:
110
111   migration-guide-*
112
113.. _`GitHub repository`: https://github.com/zephyrproject-rtos/zephyr
114.. _`GitHub tagged releases`: https://github.com/zephyrproject-rtos/zephyr/tags
115.. _`Zephyr 2.7.5`: https://docs.zephyrproject.org/2.7.5/
116.. _`Zephyr 3.5.0`: https://docs.zephyrproject.org/3.5.0/
117.. _`Zephyr 3.6.0`: https://docs.zephyrproject.org/3.6.0/
118