title: How to export excel file with xlsx extension in displaytag
body: <p>We used <strong>displaytag</strong> for exporting the files in <strong>xls</strong> format but I want it in <strong>xlsx</strong> format. Is there any way to convert the excel file to new format?</p>
  
  <p>I change the extension in display tag from <strong>xls to xlsx</strong> </p>
  
  <pre><code>&lt;display:setProperty name="export.excel" value="true"/&gt;
  &lt;display:setProperty name="export.excel.filename" value="assignedUserGroup.xlsx" /&gt;
  </code></pre>
  
  <p>but it gives me <code>"File extension is not valid"</code> when I opened it in office 2007 or 2010.</p>