Edit File: Flush.php
<?php use Twig\Node\FlushNode; class_exists('Twig\Node\FlushNode'); @trigger_error(sprintf('Using the "Twig_Node_Flush" class is deprecated since Twig version 2.7, use "Twig\Node\FlushNode" instead.'), E_USER_DEPRECATED); if (\false) { /** @deprecated since Twig 2.7, use "Twig\Node\FlushNode" instead */ class Twig_Node_Flush extends FlushNode { } }