ASCII認識

ErrorMsg: System.InvalidOperationException: 產生 XML 文件時發生錯誤。 ---> System.ArgumentException: '' (十六進位值 0x08) 是無效的字元。

public ActionResult test1(string xmlData = "")
{
    Data oData = new Data();
    try
    {
        oData.inputText = "測試_測試測試測試測試測試";

        // 序列化為XML。
        System.Xml.Serialization.XmlSerializer xmlSerializer = new System.Xml.Serialization.XmlSerializer(oData.GetType());
        XmlWriterSettings xmlSettings = new XmlWriterSettings();

        xmlSettings.Encoding = Encoding.GetEncoding("Big5");
        xmlSettings.Indent = false;
        xmlSettings.OmitXmlDeclaration = false;

        using (StringWriter szWriter = new StringWriter())
        {
            using (XmlWriter xmlWriter = XmlWriter.Create(szWriter, xmlSettings))
            {
                xmlSerializer.Serialize(xmlWriter, oData);
            }

            xmlData = szWriter.ToString();
        }
    }
    catch (Exception e)
    {
        return Content(e.Message);
    }


    return Content(xmlData);
}