Fatal error: Cannot use 'String' as class name as it is reserved in /home/paccsuccess/public_html/lib/Cake/Utility/String.php on line 27

Fatal error: Uncaught Error: Class 'String' not found in /home/paccsuccess/public_html/lib/Cake/Utility/Debugger.php:342 Stack trace: #0 /home/paccsuccess/public_html/lib/Cake/Utility/Debugger.php(747): Debugger::trace(Array) #1 /home/paccsuccess/public_html/lib/Cake/Error/ErrorHandler.php(200): Debugger->outputError(Array) #2 [internal function]: ErrorHandler::handleError(2, 'session_start()...', '/home/paccsucce...', 60, Array) #3 /home/paccsuccess/public_html/app/Vendor/facebook-php-sdk-master/src/facebook.php(60): session_start() #4 /home/paccsuccess/public_html/app/Controller/AppController.php(68): Facebook->__construct(Array) #5 /home/paccsuccess/public_html/lib/Cake/Event/CakeEventManager.php(248): AppController->beforeFilter(Object(CakeEvent)) #6 /home/paccsuccess/public_html/lib/Cake/Controller/Controller.php(670): CakeEventManager->dispatch(Object(CakeEvent)) #7 /home/paccsuccess/public_html/lib/Cake/Error/ExceptionRenderer.php(156): Controller->startupProcess() #8 /home/paccsuccess/public_html/lib/Cake/Error/Ex in /home/paccsuccess/public_html/lib/Cake/Utility/Debugger.php on line 342