Writing MemoryStream to Response Object

I had the same problem and the only solution that worked was:

Response.Clear();
Response.ContentType = "Application/msword";
Response.AddHeader("Content-Disposition", "attachment; filename=myfile.docx");
Response.BinaryWrite(myMemoryStream.ToArray());
// myMemoryStream.WriteTo(Response.OutputStream); //works too
Response.Flush();
Response.Close();
Response.End();

Assuming you can get a Stream, FileStream or MemoryStream for instance, you can do this:

Stream file = [Some Code that Gets you a stream];
var filename = [The name of the file you want to user to download/see];

if (file != null && file.CanRead)
{
    context.Response.AddHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");
    context.Response.ContentType = "application/octet-stream";
    context.Response.ClearContent();
    file.CopyTo(context.Response.OutputStream);
}

Thats a copy and paste from some of my working code, so the content type might not be what youre looking for, but writing the stream to the response is the trick on the last line.

Instead of creating the PowerPoint presentation in a MemoryStream write it directly to the Response.OutputStream. This way you don't need to be wasting any memory on the sever as the component will be directly streaming the output to the network socket stream. So instead of passing a MemoryStream to the function that is generating this presentation simply pass the Response.OutputStream.

Try with this

Response.Clear();
Response.AppendHeader("Content-Type", "application/vnd.openxmlformats-officedocument.presentationml.presentation");
Response.AppendHeader("Content-Disposition", string.Format("attachment;filename={0}.pptx;", getLegalFileName(CurrentPresentation.Presentation_NM)));
Response.Flush();                
Response.BinaryWrite(masterPresentation.ToArray());
Response.End();