I’ve upgraded to new version of twig/twig 3.x.x. As of twig version 3.0 Twig_Extension is deprecated. So I’m getting next with "whiteoctober/breadcrumbs-bundle" !! In BreadcrumbsExtension.php line 12: !! !! Attempted to load class "Twig_Extension" from the global namespace. !! Did you forget a "use" statement? Any suggestion how to fix this? Source: Symfony4..