esp-idf/SUPPORT_POLICY.md

The latest support policy for ESP-IDF can be found at [https://github.com/espressif/esp-idf/blob/master/SUPPORT_POLICY.md](https://github.com/espressif/esp-idf/blob/master/SUPPORT_POLICY.md)

Support Period Policy
=====================

* [中文版](./SUPPORT_POLICY_CN.md)

Each ESP-IDF major and minor release (V4.1, V4.2, etc) is supported for
30 months after the initial stable release date.

Supported means that the ESP-IDF team will continue to apply bug fixes,
security fixes, etc to the release branch on GitHub, and periodically
make new bugfix releases as needed.

Support period is divided into "Service" and "Maintenance" period:

| Period      | Duration     | Recommended for new projects?         |
| -------     | ------------ | ------------------------------------- |
| Service     | 12 months    | Yes                                   |
| Maintenance | 18 months    | No                                    |

During the Service period, bugfixes releases are more frequent. In some cases,
support for new features may be added during the Service period (this is
reserved for features which are needed to meet particular regulatory
requirements or standards for new products, and which carry a very low risk of
introducing regressions.)

During the Maintenance period, the version is still supported but only bugfixes
for high severity issues or security issues will be applied.

Using an “In Service” version is recommended when starting a new project.

Users are encouraged to upgrade all projects to a newer ESP-IDF release before
the support period finishes and the release becomes End of Life (EOL). It is our
policy to not continue fixing bugs in End of Life releases.

Pre-release versions (betas, previews, `-rc` and `-dev` versions, etc)
are not covered by any support period. Sometimes a particular feature is
marked as "Preview" in a release, which means it is also not covered
by the support period.

The ESP-IDF Programming Guide has information about the
[different versions of ESP-IDF](https://docs.espressif.com/projects/esp-idf/en/latest/versions.html)
(major, minor, bugfix, etc).

Example
-------

ESP-IDF V3.3 was released in September 2019. It will be supported for 30 months
until February 2022.

- The first V3.3 release was `v3.3` in September 2019.
- The ESP-IDF team continues to backport bug fixes, security fixes,
  etc to the release branch `release/v3.3`.
- Periodically stable bugfix releases are created from the release
  branch. For example `v3.3.1`, `v3.3.2`, etc. Users are encouraged to
  always update to the latest bugfix release.
- V3.3 bugfix releases continue until February 2022, when all V3.3.x
  releases become End of Life.

Existing Releases
-----------------

ESP-IDF release V4.1 and all newer releases will follow this support period
policy. The support period for each release will be announced when the release
is made.

For releases made before the current support period policy was announced, the
original support periods apply:

* ESP-IDF V4.0.x will be supported until October 2021
* ESP-IDF V3.3.x will be supported until February 2022
* ESP-IDF versions before V3.3 are already End of Life.

Policy History
--------------

* September 2019. This policy split ESP-IDF releases into Standard and Long Term
  Support.
* July 2020. All releases from now will have the same support period, which is
  equal to the previous Long Term Support period. Added “In Service” period,
  during which versions will receive more updates.