404. That’s an error.

The requested URL /catalog/product_compare/add/product/691/uenc/aHR0cDovL3d3dy5sb2phbnV0cml2aWRhLmNvbS9kaWRhdGljb3MvZmFudG9jaGVzL2ZhbnRvY2hlLTk1Lmh0bWw,/ was not found on this server. That’s all we know.