C#

// Get the object used to communicate with the server.
FtpWebRequest request = (FtpWebRequest)WebRequest.Create("XXX" + Path.GetFileName(this.txtUploadFile.Text));
request.Method = WebRequestMethods.Ftp.UploadFile;

// This example assumes the FTP site uses anonymous logon.
request.Credentials = new NetworkCredential ("XXX","XXX");
request.UseBinary = true;
request.UsePassive = false;
request.KeepAlive = false;
            
// Copy the contents of the file to the request stream.
StreamReader sourceStream = new StreamReader(this.txtUploadFile.Text);
byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());  

sourceStream.Close();
request.ContentLength = fileContents.Length;

Stream requestStream = request.GetRequestStream(); // Error occurring in here

requestStream.Write(fileContents, 0, fileContents.Length);
requestStream.Close();

FtpWebResponse response = (FtpWebResponse)request.GetResponse();