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=5510352483&hash=ac8d8fe8f2a1e4eb9ca4a91a551d1a12&redirect_to=https%3A%2F%2Fu.limo%2F1191%2F' caused an error:

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