关于"XML 文档(2, 2)中有错误：不应有 <xml xmlns=''>"错误

<?xml version="1.0" encoding="utf-8"?>
<Config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Enabled>true</Enabled>
  <serverURL>http://127.0.01/Version.xml</serverURL>
  <updateFileList updateInfo="更新说明信息">
    <localFile fileName="bb.exe" fileVersion="" />
  </updateFileList>
</Config>

XmlSerializer xmlSerializer = new XmlSerializer(typeof(configuration));
            StreamWriter streamWriter = new StreamWriter(file);
            xmlSerializer.Serialize(streamWriter, this);
            streamWriter.Close();