404. That’s an error.
The requested URL /add?feedurl=http://mfxmzsyy.no2.35nic.com/cn/rss/rss_menu_90.xml was not found on this server. That’s all we know.
/add?feedurl=http://mfxmzsyy.no2.35nic.com/cn/rss/rss_menu_90.xml