Error: 404 Not Found

Sorry, the requested URL 'http://u.limo/wp-admin/admin-ajax.php?channel_id=social_wechat&action=xh_social_channel&tab=login_redirect_to_authorization_uri&xh_social_channel=44368a18eb&notice_str=1324935004&hash=163667ef9b753311ffda79295480952b&redirect_to=https%3A%2F%2Fu.limo%2F14661%2F' caused an error:

Not found: '/wp-admin/admin-ajax.php'