Symfony 5.4.0 and 6.0.0 have been released a few days ago. As for any other Symfony release, our backward compatibility promise applies and this means that you should be able to upgrade easily to 5.4 without changing anything in your code.
During the last couple of months, we've blogged about the great 5.4 new features. I highly recommend you to read these articles about Symfony 5.4 as they contain the major changes for this new version:
