404. That’s an error.
The requested URL /catalog/product_compare/add/product/5490/uenc/aHR0cHM6Ly9zaW1wbGEuYXo6ODA4MC9xYXJhZ2lsZWxpLWRlbmxpLWJpdGtpbGVybGUtcGVjLTExNHFyLmh0bWw,/form_key/Ibf5TVe9DUSFmJNo/
was not found on this server. That’s all we know.