WebAPI 2 exports Excel,PDF that corupted when deploy on IIS 7/8 but work normally in IIS 10 on my local machine

Question

WebAPI 2 exports Excel,PDF that corupted when deploy on IIS 7/8 but work normally in IIS 10 on my local machine. Here is the excel file when I open it enter image description here

Here is my code to render excel

[HttpPost]
    [Route("api/ThiSinhDuThi/ExportExcel")]
    public HttpResponseMessage ExportExcel()
    {

        string filepath = HttpContext.Current.Server.MapPath("~/Excel_Template/BieuDSTSDuThi.xls");
        //FileInfo template = new FileInfo(filepath);
        HSSFWorkbook hssfwb;
        using ( FileStream file = new FileStream(filepath, FileMode.Open, FileAccess.Read) )
        {
            hssfwb = new HSSFWorkbook(file);
            file.Close();
        }
       
        using ( var memoryStream = new MemoryStream() ) //creating memoryStream
        {
            hssfwb.Write(memoryStream);
          
            var response = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new ByteArrayContent(memoryStream.ToArray())
            };
            
            response.Content.Headers.ContentType = new MediaTypeHeaderValue
                   ("application/vnd.ms-excel");
            response.Content.Headers.ContentDisposition =
                   new ContentDispositionHeaderValue("attachment")
                   {
                       FileName = "DSThiSinhDuThi.xls"
                   };
            
            return response;
        }
        //return stream;


    }

Answer 1

That seems too human readable for xls...maybe it's supposed to be.xlsx to open properly...though you could upload a file somewhere to check maybe?

Or if that is a response, which it probably more is, then try to see if the attachment part which isn't visible in the browser once copied in an xls file works...

I suspect you're getting a content that's not supposed to be be used directly from a browser but some client app maybe or it's getting serialized when it shouldn't be into JSON on IIS7/8 (ie the error is more likely up stream in the web server setup in some output formatter than in that code)?