XmlTextWriter myXmlTextWriter = new XmlTextWriter("Online.xml", System.Text.Encoding.UTF8);
myXmlTextWriter.Formatting = Formatting.Indented;
myXmlTextWriter.WriteElementString("name", null, name);
myXmlTextWriter.Flush();
myXmlTextWriter.Close();

FtpClient ftplib = new FtpClient();

        try
        {
            ftplib.connect("server","login","pass");
            ftplib.upload("Online.xml", "");
        }
        finally
        {            
                ftplib.disconnect();
        }

The process cannot access the file 'Online.xml' because it is being used by another process.