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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Sha1395Asked:
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Shaun KlineLead Software EngineerCommented:
Not sure if this is the issue, but I noticed in your comments that you want to read in 2kb (2 * 1024 = 2048) increments, but you are actually reading in 4kb increments (4 * 1024 = 4096). There could also be a size/time duration issue as you state that this occurs more frequently with multiple files uploads. You can test this by comparing the total size of the files and playing with files of different sizes.
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Gary DavisDir Internet SvcsCommented:
Try changing the KeepAlive property to true.

Gary Davis
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Sha1395Author Commented:
Thanks gardavis and Shaun_Kline. Tried with both your suggestion but it works only after KeepAlive property set True.

Thanks again for your help.

I have a question for you gardavis, if i keep the connection Alive,how many connection will open at the same time ? is this any performance deficiency am gonna face ?

Thanks in advance
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Gary DavisDir Internet SvcsCommented:
I am not sure but I really don't think it should be an issue.
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