In this talk I will explain how we started with a poorly tested legacy project with Symfony 3.4 and PHP 7.2 and we took it all the way up to Symfony 7 and PHP 8.3. We will talk about all the steps that we took, all the tools that we used, the difficulties that we found along the way and the benefits that we received. The talk will include a lot of samples of the changes that we had to apply at all levels. If we could do it, you can (and should) do it!!