This document details the changes that you need to make to your code when upgrading from one version to another.

• Custom Handlers

  The interfaces SerializationHandlerInterface, and DeserializationHandlerInterface have been removed. Instead, you can now use either an event listener, or the new handler concept. As a general rule, if your handler was registered for a specific type, you would use the new handler system, if you instead were handling an arbitrary number of possibly unknown types, you would use the event system.

  Please see the documentation for how to set-uup one of these.