404. That’s an error.
The requested URL /catalog/product_compare/add/product/1000/uenc/aHR0cDovL3d3dy5idXlpbmdmdXJuaXR1cmUuY28udWsvb2ZmaWNlLWZ1cm5pdHVyZS9maWxpbmctY2FiaW5ldHM,/form_key/tskP3jqFuSwX4fFl/
was not found on this server. That’s all we know.