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=5970378d9f&notice_str=5211551802&hash=6e8a97ca23750896d75c93024e530267&redirect_to=https%3A%2F%2Fu.limo%2Fhelp%2F' caused an error:

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