The following code can uplaod text files. When i upload a binary file
it fail.

I might be:
1) using the wrong Encoding
2) will have to System.Convert.ToBase64String the content of the
binary file

Any help / suggestions would be much appreciated. Already spend a lot
of time on this.

Regards, Gert

Here is the console application code:

static void Main(string[] args)
       {
           UploadImageFile(@"C:\imagetest.JPG"); //fail
           UploadImageFile(@"C:\test.txt"); //work
           Console.ReadLine();
       }

       private static string GetMultipartBoundary()
       {
           return String.Format("***********************{0}",
DateTime.Now.Ticks);
       }
       private static void UploadImageFile(string fileNameToUpLoad)
       {
           Console.WriteLine("");

Console.WriteLine("========================================");
           Console.WriteLine("UploadImageFile");

Console.WriteLine("========================================");

           string url;
           string uploadFileFormControlName;
           string boundry;
           string databoundary;
           string filetype;
           StringBuilder reqString;
           Encoding enc;
           MemoryStream oPostStream;
           BinaryWriter oPostData;
           HttpWebRequest request;
           System.IO.FileInfo fileToUpLoad;
           byte[] byteArrayBefore;
           byte[] byteArray;
           byte[] byteArrayAfter;

           reqString = new StringBuilder();
           oPostStream = new MemoryStream();
           oPostData = new BinaryWriter(oPostStream);

           url = "http://server/myreceivepage.asp";
           request =
(HttpWebRequest)System.Net.WebRequest.Create(url);

           boundry = GetMultipartBoundary();
           databoundary = "--" + boundry;
           uploadFileFormControlName = "fileinput1";
           //I think here is my problem:
           enc = Encoding.GetEncoding(1252);
           //enc = Encoding.ASCII;
           //enc = Encoding.UTF8;
           //enc = Encoding.Unicode;
           //enc = Encoding.BigEndianUnicode;
           enc = Encoding.Default;
           //enc = Encoding.UTF32;
           //enc = Encoding.UTF7;

           fileToUpLoad = new FileInfo(fileNameToUpLoad);
           //this can be enhanced, ok for testing
           switch (fileToUpLoad.Extension)
           {
               case ".txt":
                   filetype = "text/plain";
                   break;

               case ".jpg":
                   filetype = "image/pjpeg";
                   break;

               case ".gif":
                   filetype = "image/gif";
                   break;

               default:
                   filetype = "text/plain";
                   break;
           }

           //read the file content and store in byteArray[]
           long numBytes = fileToUpLoad.Length;
           FileStream fStream = new FileStream(fileNameToUpLoad,
FileMode.Open, FileAccess.Read);
           BinaryReader br = new BinaryReader(fStream, enc);
           byteArray = br.ReadBytes((int)numBytes);
           br.Close();
           fStream.Close();

           //request.Credentials = new NetworkCredential("user",
"password");

           request.Method = "POST";
           request.ContentType = "multipart/form-data;boundary=" +
boundry;

           //Start to build request string:
           //==================================
           //Should you have extra form inputs other than uploadfile
control:
           //reqString.Append("--" + boundry + "\r\n");
           //reqString.Append(databoundary + "\r\n");
           //reqString.Append("Content-Disposition: form-data; name=
\"txtAddPerson\";");
           //reqString.Append("\r\n");
           //reqString.Append("\r\n");
           //reqString.Append("myValue");
           //reqString.Append("\r\n");

           reqString.Append(databoundary + "\r\n");
           reqString.Append(string.Format("Content-Disposition: form-
data; name=\"{0}\"; ", uploadFileFormControlName));
           reqString.Append(string.Format("filename=\"{0}\"\r\n",
fileToUpLoad.Name));
           reqString.Append(string.Format("Content-Type: {0}\r\n",
filetype));
           byteArrayBefore = enc.GetBytes(reqString.ToString());

           //normally file content goes here - currently in
byteArray[]

           //Start to build request string END:
           //==================================
           reqString = new StringBuilder();
           reqString.Append("\r\n");
           reqString.AppendFormat("--{0}--\r\n", boundry);
           byteArrayAfter = enc.GetBytes(reqString.ToString());

           oPostData.Write(byteArrayBefore);
           oPostData.Write(byteArray);
           //maybe like this: ?
           //
oPostData.Write(System.Convert.ToBase64String(byteArray));
           oPostData.Write(byteArrayAfter);

           request.ContentLength = (int)oPostData.BaseStream.Length;
           request.ContentLength = byteArrayBefore.Length +
byteArray.Length + byteArrayAfter.Length;

           try
           {
               Stream stream = request.GetRequestStream();
               oPostStream.WriteTo(stream);
               StreamReader reader = new
StreamReader(request.GetResponse().GetResponseStream());
               string myOrginalRawHtml = reader.ReadToEnd();
               myOrginalRawHtml = myOrginalRawHtml.Replace("<br>", "\r
\n");
               Console.WriteLine(myOrginalRawHtml);
           }
           catch (System.Exception ex)
           {
               Console.WriteLine(ex.Message);
           }

Console.WriteLine("========================================");
           Console.WriteLine("");
       }

Thanks, gert