C#

X509Certificate certificate = new X509Certificate(@"C:\Program Files\Code-Crafters\Ability FTP Server\certs\Sync Testing Certificate.crt");

            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(_uploadURI);
            request.EnableSsl = true;
            request.Method = WebRequestMethods.Ftp.UploadFile;
            request.UsePassive = false;

            request.Credentials = new NetworkCredential(_username, _password);
            request.ClientCertificates.Add(certificate);
            Console.WriteLine("Number of Certificates: {0}", request.ClientCertificates.Count);
            
        
            try
            {
                // Copy the contents of the file to the request stream.
                StreamReader sourceStream = new StreamReader(_filepath);
                byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
                sourceStream.Close();

                request.ContentLength = fileContents.Length;
                Stream requestStream = request.GetRequestStream();<font color=red>//<--This is where the error occurs</font>
                requestStream.Write(fileContents, 0, fileContents.Length);
                requestStream.Close();

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

                Console.WriteLine("Upload File Complete, status {0}", response.StatusDescription);
            }
            catch (WebException e)
            {
                FtpWebResponse res = (FtpWebResponse)e.Response;
                string error = res.StatusDescription;
                Console.WriteLine(error.ToString());
            }