I'm having a problem I can see other people have got, but haven't been able to find a solution yet.
I can't open the generated Excel file in Excel (Nor on Mac or Windows), only if I save it to the server first.
I've looked for any addtional echo's or so, that could generate premature output, but there's nothing there. And as far as I can see, php_zip is enabled.
The warning I get is
ZipArchive::open(): Unable to access php://output in PHPExcel/Writer/Excel2007.php
Fatal Error: Uncaught exception 'Exception' with message 'Could not open php://output for writing' in PHPExcel/Writer/Excel2007.php:248 Stack trace:#0