// note the HTML Element name in this case the file must match the HttpPostedFileBase // variable name or you'll always get a numm public async Task <ActionResult> Download(string theFilePath) { System.IO.Stream blobInfo = null; if (ModelState.IsValid) { if (!String.IsNullOrWhiteSpace(theFilePath)) { blobInfo = await AzureStorageHelper.DownloadBlobAsyncSecure(theFilePath); Trace.TraceInformation("the uri to the file is {0}", theFilePath); } //ViewBag.blobUri = blobInfo.Uri.ToString(); } // get MIME type based on extension https://msdn.microsoft.com/en-us/library/system.web.mimemapping.getmimemapping string fileType = MimeMapping.GetMimeMapping(theFilePath); return(this.File(blobInfo, fileType)); //return View(); }