Deprecated the ChoiceLoaderInterface implementation in CountryType, LanguageType, LocaleType and CurrencyType, use the choice_loader option instead.

Before:

class MyCountryType extends CountryType
{
    public function loadChoiceList()
    {
        // override the method
    }
}

After:

class MyCountryType extends AbstractType
{
    public function getParent()
    {
        return CountryType::class;
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefault('choice_loader', ...); // override the option instead
    }
}

Added help option to the form field. If you have custom Form extension for it, you should remove it. Also remove it from the custom form theme.

Deprecated bundle:controller:action and service:action syntaxes to reference controllers. Use serviceOrFqcn::method instead where serviceOrFqcn is either the service ID when using controllers as services or the FQCN of the controller.

Before:

bundle_controller:
    path: /
    defaults:
        _controller: FrameworkBundle:Redirect:redirect

service_controller:
    path: /
    defaults:
        _controller: app.my_controller:myAction

After:

bundle_controller:
    path: /
    defaults:
        _controller: Symfony\Bundle\FrameworkBundle\Controller\RedirectController::redirectAction

service_controller:
    path: /
    defaults:
        _controller: app.my_controller::myAction

Deprecated Symfony\Bundle\FrameworkBundle\Controller\ControllerNameParser

Warming up a router in RouterCacheWarmer that does not implement the WarmableInterface is deprecated and will not be supported anymore in 5.0.

The RequestDataCollector class has been deprecated. Use the Symfony\Component\HttpKernel\DataCollector\RequestDataCollector class instead.