Fatal error: Uncaught Error: Call to undefined function post_is_in_descendant_category() in /www/users/HA522362/WEB/wp-content/themes/M-01/single.php:12 Stack trace: #0 /www/users/HA522362/WEB/wp-includes/template-loader.php(74): include() #1 /www/users/HA522362/WEB/wp-blog-header.php(19): require_once('/www/users/HA52...') #2 /www/users/HA522362/WEB/index.php(17): require('/www/users/HA52...') #3 {main} thrown in /www/users/HA522362/WEB/wp-content/themes/M-01/single.php on line 12