See `UPGRADE-3.0.md` for information on how to upgrade and `CHANGELOG.md` for a complete list of changes. Big Changes: - PHP 5.6 or 7.0+ are now required - PHP 7's error exceptions are actual handled by `DefaultConsumer` - NativeSerializer signs messages by default, SigningSerializer was removed - MessageExecutor and `HandlerResolver` were removed in favor of a single `MessageHandler` interface. See the upgrade guide for how this changes your code. - `DefaultConsumer` is no longer `final`. - There is now a new `AbstractConsumer` that provides everything but a `once` method.