Sending file over HttpContext causes browser to hang

Question

I am sending a file to the user using a HttpHandler. On all browsers, after viewing/downloading the file at least once, the browser/application on subsequent views/downloads hangs. Here is the code:

    private void TransmitFile(HttpContext context, string filePath, string downloadName, bool forceDownload)
    {
        if (File.Exists(filePath))
        {
            string fileName = System.IO.Path.GetFileName(filePath);
            string extension = Path.GetExtension(filePath);
            FileInfo fileInfo = new FileInfo(filePath);

            // set the response info/headers
            context.Response.ClearContent();
            context.Response.ClearHeaders();
            context.Response.AddHeader("Content-Length", fileInfo.Length.ToString());
            if (forceDownload)
            {
                context.Response.AddHeader("Content-Disposition", "attachment; filename=" + downloadName.Replace(" ", "_") + extension);
                context.Response.BufferOutput = false;
            }

            string type = "";
            // set known types based on file extension  
            if (extension != null)
            {
                switch (extension.ToLower())
                {
                    case ".tif":
                    case ".tiff":
                        type = "image/tiff";
                        break;
                    case ".jpg":
                    case ".jpeg":
                        type = "image/jpeg";
                        break;
                    case ".gif":
                        type = "image/gif";
                        break;
                    case ".doc":
                    case ".rtf":
                        type = "Application/msword";
                        break;
                    case "pdf":
                        type = "Application/pdf";
                        break;
                    case "png":
                        type = "image/png";
                        break;
                    case "bmp":
                        type = "image/bmp";
                        break;
                    default:
                        type = "application/octet-stream";
                        break;
                }
            }

            context.Response.ContentType = type;
            context.Response.TransmitFile(filePath);
            context.Response.Flush();
        }
        else
        {
            Immersive.Diagnostics.Log.Warn("Requested file does not exist: " + filePath, this);
            Immersive.Diagnostics.Log.Warn("", this);
        }
    }

I have read that calling Response.Close() and Response.End() is not a good idea? Have tried both leaving in, and removing, and it still happens.

EDIT:

It seems that TransmitFile has known issues. A more thorough explanation can be found at: http://www.improve.dk/blog/2008/03/29/response-transmitfile-close-will-kill-your-application

I removed TransmitFile and changed to WriteFile, and it now works perfectly.

context.Response.WriteFile(filePath);
context.Response.Flush();
context.Response.Close();

Answer 1

This may be a known issue if the server you're downloading from runs Windows Server 2003 SP1.

Here is a hotfix: http://support.microsoft.com/kb/902780

Also, check if you have OutputCache enabled on the page, if so, try the download again without it.

Answer 2

Any reason you're not using the buffering? You're Flush()ing it even though you aren't using it. And yes, I think you should also do a Response.End() after the Flush().

Let me know if this works and maybe I can run some tests of my own.