Fatal error: Uncaught Error: Class 'Es_Workflow_Rule' not found in /var/www/wordpress/wp-content/plugins/email-subscribers/lite/includes/workflows/rules/abstracts/class-es-rule-number-abstract.php:15 Stack trace: #0 /var/www/wordpress/wp-content/plugins/email-subscribers/lite/includes/class-email-subscribers.php(995): require_once() #1 /var/www/wordpress/wp-content/plugins/email-subscribers/lite/includes/class-email-subscribers.php(1365): Email_Subscribers->load_dependencies() #2 /var/www/wordpress/wp-content/plugins/email-subscribers/email-subscribers.php(439): Email_Subscribers::instance() #3 /var/www/wordpress/wp-content/plugins/email-subscribers/email-subscribers.php(444): ES() #4 /var/www/wordpress/wp-settings.php(517): include_once('/var/www/wordpr...') #5 /var/www/wordpress/wp-config.php(45): require_once('/var/www/wordpr...') #6 /var/www/wordpress/wp-load.php(50): require_once('/var/www/wordpr...') #7 /var/www/wordpress/wp-blog-header.php(13): require_once('/var/www/wordpr...') #8 /var/www/wordpress/index.php(17): in /var/www/wordpress/wp-content/plugins/email-subscribers/lite/includes/workflows/rules/abstracts/class-es-rule-number-abstract.php on line 15