404. That’s an error.
The requested URL /catalog/product_compare/add/product/2207/uenc/aHR0cDovL3d3dy5idXlpbmdmdXJuaXR1cmUuY28udWsvYmVkcm9vbS1mdXJuaXR1cmUvYmVkcm9vbS1zZXRz/form_key/xz8YgASyRLWtRBC9/
was not found on this server. That’s all we know.