The Release Process

The Release Process

This document explains the release process of the Symfony project (i.e. the code hosted on the main symfony/symfony Git repository).

Symfony manages its releases through a time-based model and follows the Semantic Versioning strategy:

  • A new Symfony minor version (e.g. 2.8, 3.2, 4.1) comes out every six months: one in May and one in November;
  • A new Symfony major version (e.g., 3.0, 4.0) comes out every two years and it's released at the same time of the last minor version of the previous major version.

Development

The full development period for any major or minor version lasts six months and is divided into two phases:

  • Development: Four months to add new features and to enhance existing ones;
  • Stabilization: Two months to fix bugs, prepare the release, and wait for the whole Symfony ecosystem (third-party libraries, bundles, and projects using Symfony) to catch up.

During the development phase, any new feature can be reverted if it won't be finished in time or if it won't be stable enough to be included in the current final release.

Maintenance

Each Symfony version is maintained for a fixed period of time, depending on the type of the release. This maintenance is divided into:

  • Bug fixes and security fixes: During this period, all issues can be fixed. The end of this period is referenced as being the end of maintenance of a release.
  • Security fixes only: During this period, only security related issues can be fixed. The end of this period is referenced as being the end of life of a release.

Symfony Versions

Standard Versions

A Standard Minor Version is maintained for an eight month period for bug fixes, and for a fourteen month period for security issue fixes.

In Symfony 2.x branch, the number of minor versions wasn't constrained, so that branch ended up with nine minor versions (from 2.0 to 2.8). Starting from 3.x branch, the number of minor versions is limited to five (from X.0 to X.4).

Long Term Support Versions

Every two years, a new Long Term Support Version (usually abbreviated as "LTS") is published. Each LTS version is supported for a three year period for bug fixes, and for a four year period for security issue fixes.

Note

Paid support after the three year support provided by the community can also be bought from SensioLabs.

In the Symfony 2.x branch, the LTS versions are 2.3, 2.7 and 2.8. Starting from the 3.x branch, only the last minor version of each branch is considered LTS (e.g. 3.4, 4.4, 5.4, etc.)

Schedule

Below is the schedule for the first few versions that use this release model:

../../_images/release-process.jpg
  • Yellow represents the Development phase
  • Blue represents the Stabilization phase
  • Green represents the Maintenance period

This results in very predictable dates and maintenance periods:

Version Feature Freeze Release End of Maintenance End of Life
2.0 05/2011 07/2011 03/2013 (20 months) 09/2013
2.1 07/2012 09/2012 05/2013 (9 months) 11/2013
2.2 01/2013 03/2013 11/2013 (8 months) 05/2014
2.3 03/2013 05/2013 05/2016 (36 months) 05/2017
2.4 09/2013 11/2013 09/2014 (10 months [1]) 01/2015
2.5 03/2014 05/2014 01/2015 (8 months) 07/2015
2.6 09/2014 11/2014 07/2015 (8 months) 01/2016
2.7 03/2015 05/2015 05/2018 (36 months) 05/2019
2.8 09/2015 11/2015 11/2018 (36 months [2]) 11/2019
3.0 09/2015 11/2015 07/2016 (8 months) [3]) 01/2017
3.1 03/2016 05/2016 01/2017 (8 months) 07/2017
3.2 09/2016 11/2016 07/2017 (8 months) 01/2018
3.3 03/2017 05/2017 01/2018 (8 months) 07/2018
3.4 09/2017 11/2017 11/2020 (36 months) 11/2021
4.0 09/2017 11/2017 07/2018 (8 months) 01/2019
4.1 03/2018 05/2018 01/2019 (8 months) 07/2019
4.2 09/2018 11/2018 07/2019 (8 months) 01/2020
4.3 03/2019 05/2019 01/2020 (8 months) 07/2020
4.4 09/2019 11/2019 11/2022 (36 months) 11/2023
5.0 09/2019 11/2019 07/2020 (8 months) 01/2021
... ... ... ... ...
[1]Symfony 2.4 maintenance has been extended to September 2014.
[2]Symfony 2.8 is the last version of the Symfony 2.x branch.
[3]Symfony 3.0 is the first version to use the new release process based on five minor releases.

Tip

If you want to learn more about the timeline of any given Symfony version, use the online timeline calculator. You can also get all data as a JSON string via a URL like https://symfony.com/roadmap.json?version=2.x.

Tip

Whenever an important event related to Symfony versions happens (a version reaches end of maintenance or a new patch version is released for instance), you can automatically receive an email notification if you subscribed on the roadmap notification page.

Backwards Compatibility

Our Backwards Compatibility Promise is very strict and allows developers to upgrade with confidence from one minor version of Symfony to the next one.

Whenever keeping backward compatibility is not possible, the feature, the enhancement or the bug fix will be scheduled for the next major version.

Deprecations

When a feature implementation cannot be replaced with a better one without breaking backward compatibility, there is still the possibility to deprecate the old implementation and add a new preferred one along side. Read the conventions document to learn more about how deprecations are handled in Symfony.

Rationale

This release process was adopted to give more predictability and transparency. It was discussed based on the following goals:

  • Shorten the release cycle (allow developers to benefit from the new features faster);
  • Give more visibility to the developers using the framework and Open-Source projects using Symfony;
  • Improve the experience of Symfony core contributors: everyone knows when a feature might be available in Symfony;
  • Coordinate the Symfony timeline with popular PHP projects that work well with Symfony and with projects using Symfony;
  • Give time to the Symfony ecosystem to catch up with the new versions (bundle authors, documentation writers, translators, ...).

The six month period was chosen as two releases fit in a year. It also allows for plenty of time to work on new features and it allows for non-ready features to be postponed to the next version without having to wait too long for the next cycle.

The dual maintenance mode was adopted to make every Symfony user happy. Fast movers, who want to work with the latest and the greatest, use the standard version: a new version is published every six months, and there is a two months period to upgrade. Companies wanting more stability use the LTS versions: a new version is published every two years and there is a year to upgrade.

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