Hi! We have a mission! To make the most popular Symfony bundles (& libraries that use Symfony components) compatible with Symfony 4.
For details & instructions, see: http://symfony.com/blog/helping-prepare-for-symfony-4-bundle-support
When you create a pull request, include the text #SymfonyConHackday2017 so we can count our progress!
Also, join us on the Symfony Slack for support: http://symfony.com/slack-invite