“Excel found unreadable content” warning when opening Excel files made with PHPExcel

Question

I\'m trying to download Excel files (xlsx) using PHPExcel as follows.

require_once(\"../../phpExcel/Classes/PHPExcel.php\");
require_once(\"../../phpExcel/Cl         


        

Answer 1

This error can also be triggered by serving the file without the Content-Length headers.

Look at the example given here in php.net