Fatal error: Class 'WP_Widget' not found in /var/www/pagemasters/public_html/wp-content/plugins/formidable/pro/classes/widgets/FrmListEntries.php on line 3

Call Stack:
    0.0004     880072   1. {main}() /var/www/pagemasters/public_html/wp-content/plugins/formidable/pro/classes/widgets/FrmListEntries.php:0