404. That’s an error.

The requested URL /catalog/product_compare/add/product/1001/uenc/aHR0cDovL3d3dy5lLWdyZWVudG91cmlzbS5jb20vY29hY2gtdGFza2VyLXRvdGVzLWNoZWxzZWEuaHRtbA,,/form_key/JLPv9XQoPLxRqKHy/ was not found on this server. That’s all we know.