MySQLi Error on Editing Categories

I get the following error when I try to edit selected categories (about half of them):

Warning: mysqli::query(): (21000/1242): Subquery returns more than 1 row in /home/tornado/public_html/system/library/db/mysqli.php on line 18Notice: Error: Subquery returns more than 1 row
Error No: 1242
SELECT DISTINCT *, (SELECT GROUP_CONCAT(cd1.name ORDER BY level SEPARATOR ' > ') FROM oc_category_path cp LEFT JOIN oc_category_description cd1 ON (cp.path_id = cd1.category_id AND cp.category_id != cp.path_id) WHERE cp.category_id = c.category_id AND cd1.language_id = '1' GROUP BY cp.category_id) AS path, (SELECT DISTINCT keyword FROM oc_url_alias WHERE query = 'category_id=55') AS keyword FROM oc_category c LEFT JOIN oc_category_description cd2 ON (c.category_id = cd2.category_id) WHERE c.category_id = '55' AND cd2.language_id = '1' in /home/tornado/public_html/system/library/db/mysqli.php on line 40Notice: Trying to get property of non-object in /home/tornado/public_html/admin/model/catalog/category.php on line 213

This is a clean install of opencart version 2.0.1.0