Requête erronée: Unknown column 'undefined' in 'where clause'

SELECT * FROM mutualisation_objets WHERE id=undefined

#1 /home/clients/36be1948987b3308c6712633f2cc9852/web/cms/lib/db.php(27): obj->_error()
#2 /home/clients/36be1948987b3308c6712633f2cc9852/web/cms/controllers/mutualisation_objets_ajax.php(8): db->execQuery()