Reading a binary file and using Response.BinaryWrite()

        Response.BinaryWrite(bytes);
        Response.Flush();
        Response.Close();
        Response.End();

This works for us. We create PDFs from SQL Reporting Services.

We've used this with a lot of success. WriteFile do to the download for you and a Flush / End at the end to send it all to the client.

            //Use these headers to display a saves as / download
            //Response.ContentType = "application/octet-stream";
            //Response.AddHeader("Content-Disposition", String.Format("attachment; filename={0}.pdf", Path.GetFileName(Path)));

            Response.ContentType = "application/pdf";
            Response.AddHeader("Content-Disposition", String.Format("inline; filename={0}.pdf", Path.GetFileName(Path)));

            Response.WriteFile(path);
            Response.Flush();
            Response.End();

Since you're sending the file directly from your filesystem with no intermediate processing, why not use Response.TransmitFile instead?

Response.Clear();
Response.ContentType = "application/pdf";
Response.AddHeader("Content-Disposition",
    "attachment; filename=\"" + Path.GetFileName(path) + "\"");
Response.TransmitFile(path);
Response.End();

(I suspect that your problem is caused by a missing Response.End, meaning that you're sending the rest of your page's content appended to the PDF data.)

Just for future reference, as stated in this blog post: http://blogs.msdn.com/b/aspnetue/archive/2010/05/25/response-end-response-close-and-how-customer-feedback-helps-us-improve-msdn-documentation.aspx

It is not recommended to call Response.Close() or Response.End() - instead use CompleteRequest().

Your code would look somewhat like this:

    byte[] bytes = {};

    bytes = GetBytesFromDB();  // I use a similar way to get pdf data from my DB

    Response.Clear();
    Response.ClearHeaders();
    Response.Buffer = true;
    Response.Cache.SetCacheability(HttpCacheability.NoCache);
    Response.ContentType = "application/pdf";
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + anhangTitel);
    Response.AppendHeader("Content-Length", bytes.Length.ToString());
    this.Context.ApplicationInstance.CompleteRequest();

Please read this before using Response.TransmitFile: http://improve.dk/blog/2008/03/29/response-transmitfile-close-will-kill-your-application

Maybe you are missing a Response.close to close de Binary Stream

In my MVC application, I have enabled gzip compression for all responses. If you are reading this binary write from an ajax call with gzipped responses, you are getting the gzipped bytearray rather than original bytearray that you need to work with.

//c# controller is compressing the result after the response.binarywrite

[compress]
public ActionResult Print(int id)       
{
... 
var byteArray=someService.BuildPdf(id);
return  return this.PDF(byteArray, "test.pdf");
}

//where PDF is a custom actionresult that eventually does this:
 public class PDFResult : ActionResult
{
...
    public override void ExecuteResult(ControllerContext context)
    {
        //Set the HTTP header to excel for download
        HttpContext.Current.Response.Clear();
        //HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
        HttpContext.Current.Response.ContentType = "application/pdf";
        HttpContext.Current.Response.AddHeader("content-disposition", string.Concat("attachment; filename=", fileName));
        HttpContext.Current.Response.AddHeader("Content-Length", pdfBytes.Length.ToString());
        //Write the pdf file as a byte array to the page
        HttpContext.Current.Response.BinaryWrite(byteArray);
        HttpContext.Current.Response.End();
    }
}

//javascript

function pdf(mySearchObject) {
    return $http({
    method: 'Post',
    url: '/api/print/',
    data: mySearchObject,
    responseType: 'arraybuffer',
    headers: {
    'Accept': 'application/pdf',
    }
    }).then(function (response) {

var type = response.headers('Content-Type');
//if response.data is gzipped, this blob will be incorrect.  you have to uncompress it first.
var blob = new Blob([response.data], { type: type });
var fileName = response.headers('content-disposition').split('=').pop();

if (window.navigator.msSaveOrOpenBlob) { // for IE and Edge
    window.navigator.msSaveBlob(blob, fileName);
} else {

    var anchor = angular.element('<a/>');
    anchor.css({ display: 'none' }); // Make sure it's not visible
    angular.element(document.body).append(anchor); // Attach to document

    anchor.attr({
    href: URL.createObjectURL(blob),
    target: '_blank',
    download: fileName
    })[0].click();

    anchor.remove();
}
});

}

" var blob = new Blob([response.data], { type: type }); " This will give you that invalid/corrupt file that you are trying to open when you turn that byte array into a file in your javascript if you don't uncompress it first.

To fix this, you have a choice to either prevent gzipping this binary data so that you can properly turn it into the file that you are downloading, or you have to decompress that gzipped data in your javascript code before you turn it into a file.

In addition to Igor's Response.Close(), I would add a Response.Flush().

I also found it necessary to add the following:

Response.Encoding = Encoding.Default

If I didn't include this, my JPEG was corrupt and double the size in bytes.

But only if the handler was returning from an ASPX page. It seemed running from an ASHX this was not required.