title: Downloaded excel file not opening
body: <p>I am trying to download excel file to the location in local system but on opening the file, i am getting error:</p>
  
  <blockquote>
    <p>The file format or extension does not match.</p>
  </blockquote>
  
  <p>Although the file at backend is of same extension but i am getting the error
  PFB the code:</p>
  
  <pre><code>string ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
  Response.ContentType = ContentType;
  Response.AppendHeader("Content-Disposition", "attachment; filename="+downloadedFileName);
  
  
  downloadedFileName= "Myfile.xlsx"
  </code></pre>