404. That’s an error.

The requested URL /catalog/product_compare/add/product/17/uenc/aHR0cDovL2NsZWFudHVuaW5nLmNvbS9ibXctc2lkZS1tYXJrZXJzP21vZGU9bGlzdA,,/ was not found on this server. That’s all we know.