Fatal error: Uncaught Error: Class 'Twig_Loader_Filesystem' not found in /var/www/html/wordpress/wp-content/plugins/mailpoet/lib/Config/Renderer.php:28 Stack trace: #0 /var/www/html/wordpress/wp-content/plugins/mailpoet/lib/Subscribers/NewSubscriberNotificationMailer.php(39): MailPoet\Config\Renderer->__construct(true, false) #1 /var/www/html/wordpress/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(637): MailPoet\Subscribers\NewSubscriberNotificationMailer->__construct() #2 /var/www/html/wordpress/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(647): MailPoetGenerated\FreeCachedContainer->getSubscriberActionsService() #3 /var/www/html/wordpress/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(397): MailPoetGenerated\FreeCachedContainer->getCommentService() #4 /var/www/html/wordpress/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(407): MailPoetGenerated\FreeCachedContainer->getHooksService() #5 /var/www/html/wordpress/wp-content/plugins/mailpoet/vendor-prefixed/symfo in /var/www/html/wordpress/wp-content/plugins/mailpoet/lib/Config/Renderer.php on line 28