protected function _handleXMLHTTPCommandException(\Throwable $e)
    {
		// send xmlhttp headers
		header("Content-Type: application/json; charset=utf-8");
		
		// no cache
		header("Expires: Sat, 1 Jan 2005 00:00:00 GMT");
		header("Last-Modified: ".gmdate( "D, d M Y H:i:s")." GMT");
		header("Cache-Control: no-cache, must-revalidate");
		header("Pragma: no-cache"); 
        
        
		// get exception string (stack trace)
        $ex = $this->_getException($e, 'Error during async request');
        
        echo json_encode(array('statut'=>false, 'message'=>'Error during async request', 'exception'=>$ex));
    }