500 ошибка при редактировании тикета

$sql = "SELECT id FROM prefix_users";
$q = $modx->prepare($sql);
$q->execute();
$res = $q->fetchAll(PDO::FETCH_ASSOC);

    foreach ($res as $row) {
        $sql2 = "SELECT id FROM prefix_user_attributes WHERE internalKey=".$row['id']." LIMIT 1";
        $q2 = $modx->prepare($sql2);
        $q2->execute();
        $res2 = $q2->fetchAll(PDO::FETCH_ASSOC);
        if(count($res2)==0)
            echo $row['id'].'<br />';
    }