Fatal error: Uncaught Error: Class "Magento\Config\Block\System\Config\Form\Fieldset" not found in /var/www/magento/html/app/code/Amasty/Rules/Block/Adminhtml/System/Config/Information.php:15 Stack trace: #0 {main} thrown in /var/www/magento/html/app/code/Amasty/Rules/Block/Adminhtml/System/Config/Information.php on line 15