如何在codeigniter中将xls转换为xlsx

I am using PHPExcel for downloading the file as xlsx format. I am using codeigniter framework. Previously i am downloading xls format. At that time the file is downloaded successfully. If i am trying for downloading as xlsx format it gives the error as below image.enter image description here

My code is :

$this->load->library('Excel');
$this->excel->setActiveSheetIndex(0);
$this->excel->getActiveSheet()->setTitle('Sales Data'); 
$filename='Salesdata.xlsx';
$objWriter = PHPExcel_IOFactory::createWriter($this->excel, 'Excel2007');
header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition:attachment;filename="'.$filename.'"');
header('Cache-Control: max-age=0');
$objWriter->save('php://output');

There is no error when i am adding as xls format. It gives the error when i am adding as filename.xlsx. Any solution please.

you may continue with php Output buffers and codeigniter download helper for example :-

$filename='Salesdata.xlsx';
ob_start();
$objWriter = PHPExcel_IOFactory::createWriter($this->excel, 'Excel2007');
//force user to download the Excel file without writing it to server's HD
$objWriter->save('php://output');
$this->load->helper('download');
$excelFileContents = ob_get_clean();
force_download($filename, $excelFileContents);