So you want to upgrade to Symfony 3.0? An excellent choice! And guess what, it won't even break your app.
In this tutorial, we'll show you how to upgrade to Symfony 2.8 and then find and fix deprecated features. Then, we'll go to 3.0!
Symfony 3.0 also comes with a new directory structure. It's great, but it takes a little bit of work to move your project to it. One chapter is devoted entirely to converting to that structure.