Fatal error: Uncaught Error: Class 'WP_Sitemaps_Provider' not found in /home/crossfir/public_html/wp-includes/sitemaps/providers/class-wp-sitemaps-posts.php:17
Stack trace:
#0 {main}
thrown in /home/crossfir/public_html/wp-includes/sitemaps/providers/class-wp-sitemaps-posts.php on line 17