After updating the Moodle platform from version 3.6.2 to version 3.8.3, I get the following error:
Fatal error: Cannot redeclare forum_get_user_grades() (previously declared in /var/www/html/xxxxxxx/mod/forum/lib.php:1674) in /var/www/html/xxxxxx/mod/forum/deprecatedlib.php on line 1671