404. That’s an error.

The requested URL /catalog/product_compare/add/product/343/uenc/aHR0cDovL2NsZWFudHVuaW5nLmNvbS9ibXctMy1zZXJpZXMtc2VkYW4tOTctOTgtZTM2LWNhcmJvbi1maWJlci1raWRuZXktZ3JpbGxlLXNldC1jdC1ibXczMzY0Lmh0bWw,/ was not found on this server. That’s all we know.