Question

I am trying to serialize a custom object into xml with this code:

MatchList matchList = converter.Convert(excelStream);
XmlSerializer xmlSerializer = new XmlSerializer(typeof(MatchList));
StringWriter stringWriter = new StringWriter();
xmlSerializer.Serialize(stringWriter, matchList);
string serializedXml = stringWriter.ToString();
txtResult.Text = serializedXml;

However I get the exception above in the 2nd line:

The matchlist object is defined as:

public class MatchList
{
   public Header Header { get; set; }

   [XmlArray("Lists")]
   [XmlArrayItem("List")]
   public virtual List<List> Lists { get; set; }
}

Answer 1

[XmlArray("Lists")]
[XmlArrayItem("List")]
public virtual List<object> Lists { get; set; }

and add mark knownTypeAttribute with serializable types as object