PHPExcel File format or extension is not valid

Question

I'm using phpexcel for export my query in excel file; however after I created file(which is xslx format), I can not open my file in excel. It gives "the file format or extension is not valid. Verify that the file has not been corrupted and that the file extension matches the file format of the file" error. When I open the file in texteditor(mine is npp) I see my php file's css codes and some part of my html codes. My code is like that;

if( ! empty($_POST['export'])){
  $query = "SELECT * FROM asd ORDER BY asdf LIMIT 10";
  $headings = array('Timestamp', 'h1','h2');
      require 'Classes/PHPExcel.php';

  $objPHPExcel = new PHPExcel();
  $objPHPExcel->getActiveSheet()->setTitle('List of Users');

  $rowNumber = 1;
  $col = 'A';
  foreach($headings as $heading) {
    $objPHPExcel->getActiveSheet()->setCellValue($col.$rowNumber,$heading);
    $col++;
  }

  $rowNumber = 2;
  while ($row = mysql_fetch_row($result)) {
    $col = 'A';
    foreach($row as $cell) {
        $objPHPExcel->getActiveSheet()->setCellValue($col.$rowNumber,$cell); 
        $col++;
    }
    $rowNumber++;
  }

$objPHPExcel->getActiveSheet()->freezePane('A2');

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');

header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="userList.xlsx"');
header("Content-Transfer-Encoding: binary ");
//ob_end_clean();
//header('Cache-Control: max-age=0');

$objWriter->save('php://output');
exit();
}

I'm stucked please help. Thank you.

Answer 1

As described in the manual.... if anything else is being output to the browser, this will corrupt the output file.

Open the file in a text editor, and look for leading or trailing whitespace characters (spaces, tabs, newlines) or a BOM marker at the beginning of the output, or for any obvious PHP plaintext error messages in the content. These are the most obvious causes of this problem. Once you've identified the spurious characters, check through your script to see where that output is being generated, and remove it.

In your case, that means don't output your css and html.

EDIT

xlsx is the extension for an OfficeOpenXML Excel2007 file, not for a BIFF 8 xls file.... be consistent in your headers (mime type and file extension) and Writer

Either:

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="userList.xls"');

or

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Content-Disposition: attachment;filename="userList.xlsx"');