Warning:  [mysql error 1064] You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '))
  ORDER BY date_available DESC, file ASC, id ASC' at line 5

SELECT DISTINCT(id)
  FROM images i
    INNER JOIN image_category AS ic ON id = ic.image_id
    LEFT JOIN image_tag AS it ON id = it.image_id
  WHERE (category_id IN ())
  ORDER BY date_available DESC, file ASC, id ASC in /var/www/piwigo/include/dblayer/functions_mysqli.inc.php on line 847

Fatal error: Uncaught Error: Call to a member function fetch_assoc() on bool in /var/www/piwigo/include/dblayer/functions_mysqli.inc.php:908 Stack trace: #0 /var/www/piwigo/include/functions.inc.php(1609): query2array() #1 /var/www/piwigo/include/functions_search.inc.php(459): array_from_query() #2 /var/www/piwigo/include/functions_search.inc.php(1698): get_regular_search_results() #3 /var/www/piwigo/include/section_init.inc.php(364): get_search_results() #4 /var/www/piwigo/index.php(12): include('...') #5 {main} thrown in /var/www/piwigo/include/dblayer/functions_mysqli.inc.php on line 908