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=8addc78709&notice_str=1468324518&hash=15cc9a988b9bcfab18241e4de1ce94af&redirect_to=https%3A%2F%2Fu.limo%2Ftag%2F%25E6%2595%25B0%25E6%258D%25AE%25E5%259B%25BE%25E8%25A1%25A8%2F' caused an error:

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