Breaking: #87627 - Remove Property extensionName of AbstractController 

See forge#87627

Description 

\TYPO3\CMS\Extbase\Mvc\Controller\AbstractController::$extensionName has been removed and is no longer available in subclasses of \TYPO3\CMS\Extbase\Mvc\Controller\AbstractController, i.e. \TYPO3\CMS\Extbase\Mvc\Controller\ActionController and their derivates.

Impact 

Accessing the missing property $extensionName will throw a fatal error.

Affected Installations 

All installations that read from \TYPO3\CMS\Extbase\Mvc\Controller\AbstractController::$extensionName.

Migration 

The extension name is set in and available through the request object that is available in the controller. See \TYPO3\CMS\Extbase\Mvc\Controller\AbstractController::$request and \TYPO3\CMS\Extbase\Mvc\Request::getControllerExtensionName() for more information.