New in Symfony 3.4: Disable global form themes

In Symfony 3.4 you can disable global form themes for specific forms thanks to the new "only" keyword added to the "form_theme" Twig tag.

New in Symfony 3.4: Guard authentication improvements

In Symfony 3.4, Guard authenticators can implement a new method called supports() to better separate the responsibilities of the getCredentials() method.

New in Symfony 3.4: debug:form command

Symfony 3.4 adds a new command called debug:form to introspect all the information available for form types and their options.

New in Symfony 3.4: Local service binding

Symfony 3.4 allows binding services and parameters in local configuration files to avoid duplicating them in multiple service definitions.

New in Symfony 3.4: Services are private by default

In Symfony 3.4 services and aliases are private by default. This may require you to change some service definitions in your bundles and applications.

New in Symfony 3.4: Minimalist PSR-3 logger

Symfony 3.4 adds a minimalist PSR-3 logger so you can display, aggregate and store log messages without having to install Monolog.

New in Symfony 3.4: Improved the overriding of templates

In Symfony 3.4, there's a new directory to override third-party templates and a new feature to avoid circular exceptions when overriding and extending templates at the same time.

New in Symfony 3.4: Simpler injection of tagged services

Symfony 3.4 provides a simpler way to inject all services tagged with a specific tag, so you don't have to create a compiler pass just to do that.

New in Symfony 3.4: Form improvements

Symfony 3.4 adds new HTML5 form types ("tel" and "color"), new options for TimezoneType and support for callbacks in the delete_empty option.

New in Symfony 3.4: Defining compiler passes in the kernel

In Symfony 3.4, the kernel of the application can implement CompilerPassInterface to define a compiler pass in it.