404. That’s an error.

The requested URL /catalog/product_compare/add/product/172/uenc/aHR0cDovL2NsZWFudHVuaW5nLmNvbS9ibXcteDUtbS1wb3dlci1tLXRlY2gtc3R5bGUtc3BvcnRzLXNoaWZ0LWtub2ItZ2VudWluZS13b29kLWJydXNoZWQtYWx1bWludW0tY3QtMjIwMzg3NnctNS5odG1s/ was not found on this server. That’s all we know.