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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.
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.
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.
The maintenance document describes the boundaries of acceptable changes during maintenance.
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.
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.)
Below is the schedule for the first few versions that use this release model:
- Yellow represents the Development phase
- Blue represents the Stabilization phase
- Green represents the Maintenance period
If you want to learn more about the timeline of any given Symfony version, use the online timeline calculator.
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.
|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 (LTS)||03/2013||05/2013||05/2016 (36 months)||05/2017|
|2.4||09/2013||11/2013||09/2014 (10 months )||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 (LTS)||03/2015||05/2015||05/2018 (36 months)||05/2019|
|2.8 (LTS)||09/2015||11/2015||11/2018 (36 months )||11/2019|
|3.0||09/2015||11/2015||07/2016 (8 months )||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 (LTS)||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 (LTS)||09/2019||11/2019||11/2022 (36 months)||11/2023|
|5.0||09/2019||11/2019||07/2020 (8 months)||01/2021|
|||Symfony 2.4 maintenance has been extended to September 2014.|
|||Symfony 2.8 is the last version of the Symfony 2.x branch.|
|||Symfony 3.0 is the first version to use the new release process based on five minor releases.|
Our Backward 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.
However, Experimental Features are not part of the backward compatibility promise and their APIs can change from one minor version to the next. The changelog must explain the changes and how to upgrade.
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.
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.
This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.