Error message in XML and API with C # code

Based on this code below from previous support :

 using (WebClient client = new WebClient())
 {
     client.Headers.Add("Accept-Language", " en-US");
     client.Headers.Add("Accept", " text/html, application/xhtml+xml, */*");
     client.Headers.Add("User-Agent", "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)");

     XDocument xml = XDocument.Parse(client.DownloadString("http://api.arbetsformedlingen.se/af/v0/platsannonser/matchning?lanid=1&kommunid=180&yrkesid=2419&1&antalrader=10000"));
 }

      

        
        
        
      

    

I am getting the error

{System.Xml.XmlException} {"The data at the root level is invalid. Line 1, position 1." }

I tried to solve it, but I cannot find a solution for it.