Fatal error: Uncaught Error: Class 'IXR_Server' not found in /var/www/clients/client0/web9/web/wp-includes/IXR/class-IXR-introspectionserver.php:9 Stack trace: #0 {main} thrown in /var/www/clients/client0/web9/web/wp-includes/IXR/class-IXR-introspectionserver.php on line 9