Our Backward Compatibility Promise

Ensuring smooth upgrades of your projects is our first priority. That's why we promise you backward compatibility (BC) for all minor Symfony releases. You probably recognize this strategy as Semantic Versioning. In short, Semantic Versioning means that only major releases (such as 2.0, 3.0 etc.) are allowed to break backward compatibility. Minor releases (such as 2.5, 2.6 etc.) may introduce new features, but must do so without breaking the existing API of that release branch (2.x in the previous example).

Our Backward Compatibilty ONLY ensures the methods documented in the Reference section. I.e. all other methods / properties are considered private.

Backward compatibility breaks are tolerated if they are required to fix a security issue.