**Symfony version(s) affected**: 4.4 **Description** Actually PlainTextPasswordEnocder::isPasswordValid() throws an exception when the user has no password set (password is null) **How to reproduce** <!-- Code and/or config needed to reproduce the problem. If it's a complex bug, create a "bug reproducer" as explained in: https://symfony.com/doc/current/contributing/code/reproducer.html --> When UserInterface::password is null and the encoder is PlainTextPasswordEncoder an exception is thrown  **Possible Solution** <!--- Optional: only if you have suggestions on a fix/reason for the bug --> I think PlainTextPasswordEnocder::isPasswordValid() should return false when the user's password is null.