通过PHP下载PDF不会在手机上打开

Generating a PDF from wkhtmltopdf working great on desktop. I have a two-step process to generate the file and then download the file. The file generated opens just fine on my mobile device (when I e-mail it) but using a PHP script, I am unable to open after download.

In other words, it's not the PDF, it's the PHP download that's causing problems. The file downloads with the appropriate name, but won't open in mobile.

Galaxy S5 w/ Chrome (up-to-date).

The download is started with javascript:

window.location = 'savePDF.php?file=' + filename + '&fileName=' + nameString;

And here's the PHP script:

<?php
$file = $_GET['file'];

header('Pragma: public',true);
header('Expires: 0');
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Content-Type: application/octet-stream");
header('Content-Disposition: attachment; filename="'.$_GET['fileName'].'.pdf"');
header("Content-Transfer-Encoding: binary");
header('Content-Length: ' . filesize($file));
readfile($file);
unlink($file);
?>

EDIT: unlink($file) added to code to show that aspect.

Figured it out. Thanks to everyone for helping me debug (on mobile without dev tools it is a pain).

I was unlink($file); right after readfile($file) and for some reason on mobile (when it was asking what I wanted to do with the file before downloading) it was deleting the temporary file before reading the entire contents. Instead, I added:

exec("php cleantmp.php $tmpfile > NUL &");

and created cleantmp.php:

<?php
if (php_sapi_name() == 'cli') {
    sleep(10);

    unlink($argv[1]);
}
?>

Which now runs in the background and deletes the temp files after 10 seconds.

Thanks again for your help CBroe