Excel File download through web api. Getting corrupt

问题

I am trying to download a excel file through Web API (using Entity framework). The download is working but I am getting some error dialog about file corrupt when trying to open the file.

Web API code as below:

  public HttpResponseMessage GetValue(int ID, string name)
    {

    MemoryStream stream;
    try {
        using (DataContext db = new DataContext()) {
            dynamic fileObj = (from c in db.FileList c.ID == IDc).ToList();
            stream = new MemoryStream(fileObj(0).File);
            HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
            result.Content = new StreamContent(stream);
            result.Content.Headers.ContentType = new MediaTypeHeaderValue(fileObj(0).FileContentType);
            result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = name };
            return result;
        }
    } catch (Exception ex) {
        return Request.CreateResponse(HttpStatusCode.InternalServerError);
    }
}

It opens the file with two error dialog and following message.

Excel completed file level validation and repair. Some parts of this workbook may have been repaired or discarded