404. That’s an error.
The requested URL /catalog/product_compare/add/product/1621/uenc/aHR0cDovL2pvc2VhbGRvLmNvbS5ici9wcmVzZW50ZXMvZm9uZXMtZGUtb3V2aWRvLmh0bWw_bW9kZT1saXN0/form_key/2xH3jiWET3Fzurfm/
was not found on this server. That’s all we know.