UPGRADE FROM 4.x to 5.0

Config

Added the getChildNodeDefinitions() method to ParentNodeDefinitionInterface.
The Processor class has been made final

Console

Removed the setCrossingChar() method in favor of the setDefaultCrossingChar() method in TableStyle.
Removed the setHorizontalBorderChar() method in favor of the setDefaultCrossingChars() method in TableStyle.
Removed the getHorizontalBorderChar() method in favor of the getBorderChars() method in TableStyle.
Removed the setVerticalBorderChar() method in favor of the setVerticalBorderChars() method in TableStyle.
Removed the getVerticalBorderChar() method in favor of the getBorderChars() method in TableStyle.

DependencyInjection

Removed the TypedReference::canBeAutoregistered() and TypedReference::getRequiringClass() methods.

EventDispatcher

The TraceableEventDispatcherInterface has been removed.

FrameworkBundle

Removed support for 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

Removed Symfony\Bundle\FrameworkBundle\Controller\ControllerNameParser.
Warming up a router in RouterCacheWarmer that does not implement the WarmableInterface is not supported anymore.
The RequestDataCollector class has been removed. Use the Symfony\Component\HttpKernel\DataCollector\RequestDataCollector class instead.

HttpFoundation

The $size argument of the UploadedFile constructor has been removed.
The getClientSize() method of the UploadedFile class has been removed.
The getSession() method of the Request class throws an exception when session is null.

Security

The ContextListener::setLogoutOnUserChange() method has been removed.
The Symfony\Component\Security\Core\User\AdvancedUserInterface has been removed.
The ExpressionVoter::addExpressionLanguageProvider() method has been removed.

SecurityBundle

The logout_on_user_change firewall option has been removed.
The switch_user.stateless firewall option has been removed.
The SecurityUserValueResolver class has been removed.

Translation

The FileDumper::setBackup() method has been removed.
The TranslationWriter::disableBackup() method has been removed.

TwigBundle

The default value (false) of the twig.strict_variables configuration option has been changed to %kernel.debug%.

Validator

The Email::__construct() 'strict' property has been removed. Use 'mode'=>"strict" instead.
Calling EmailValidator::__construct() method with a boolean parameter has been removed, use EmailValidator("strict") instead.
Removed the checkDNS and dnsMessage options from the Url constraint.

Workflow

add method has been removed use addWorkflow method in Workflow\Registry instead.
SupportStrategyInterface has been removed, use WorkflowSupportStrategyInterface instead.
ClassInstanceSupportStrategy has been removed, use InstanceOfSupportStrategy instead.

Uh oh!