The underlying connection was closed: The server committed a protocol violation

I was uploading my file using below code,it works fine but some time it throws this error"The underlying connection was closed: The server committed a protocol violation" and stop the process ,when i run it again it upload file with out any issue.

One thing i noticed,if i run this process to upload multiple files then i get this error sometime,if i do less than 5 files then it works fine,any idea where and what i have to look in to it.

I was searchin google nothing found solid solution for this,even one of the msdn blog saying its a bug in FTPwebrequest but not sure.

Thanks in Advance

 

                    FileInfo fileInf = new FileInfo(filename);
                    FtpWebRequest reqFTP;
    
                    // Create FtpWebRequest object from the Uri provided
                    reqFTP = (FtpWebRequest)FtpWebRequest.Create
                             (new Uri(path + fileInf.Name));
    
                    
                    // Provide the WebPermission Credintials
                     reqFTP.Credentials = new NetworkCredential(user, pwd);
    
                    // By default KeepAlive is true, where the control connection
                    // is not closed after a command is executed.
                    reqFTP.KeepAlive = false;
    
    
                    // Specify the command to be executed.
                    reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
    
                    // Specify the data transfer type.
                    reqFTP.UseBinary = true;
                    reqFTP.Timeout = -1;
                    reqFTP.UsePassive = true;
    
    
                    // Notify the server about the size of the uploaded file
                    reqFTP.ContentLength = fileInf.Length;
    
                    // The buffer size is set to 2kb
                    int buffLength = 4096;
                    byte[] buff = new byte[buffLength];
                    int contentLen;
    
                    // Opens a file stream (System.IO.FileStream) to read the file
                    // to be uploaded
                    FileStream fs = fileInf.OpenRead();
                  
                    
                    try
                    {
                        // Stream to which the file to be upload is written
                        Stream strm = reqFTP.GetRequestStream();
    
                        // Read from the file stream 2kb at a time
                        contentLen = fs.Read(buff, 0, buffLength);
    
                        // Till Stream content ends
                        while (contentLen != 0)
                        {
                            // Write Content from the file stream to the FTP Upload
                            // Stream
                            strm.Write(buff, 0, contentLen);
                            contentLen = fs.Read(buff, 0, buffLength);
                        }
    
                        // Close the file stream and the Request Stream
                        strm.Close();
                        fs.Close();
                    }

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