Trouble uploading files with special characters - php

Question

I have coded a little upload script that works just fine in every case when I use it, but I always get messages from my client that he gets an error that I die() when the upload goes wrong/doesn't work.
I believe that this was caused by the special characters they use. Because they are Austrians they have special chars like äÄöÖüÜß in their filenames. Plus they use whitespaces in there filenames.
Therefore I used a regex to replace special characters into underlines(_).
$moveFile = function($tmpname,$name,$time) {
// the regex to resolve the special chars problem
$name = preg_replace('/[^a-zA-Z0-9\.]/s', '_', $name);
if (!move_uploaded_file($tmpname,'assets/siteContents/bewerbungen/'.$time.'_'.$name)) {
die('something went wrong while uploading');
}
};
// move application_files__image
$moveFile($_FILES['application_files__image']['tmp_name'],
$_FILES['application_files__image']['name'],
$time);
// move application_files__image
$moveFile($_FILES['application_files__cv']['tmp_name'],
$_FILES['application_files__cv']['name'],
$time);
// move application_files__certificates
if (count($_FILES['application_files__certificates']['name'])) {
foreach ($_FILES['application_files__certificates']['name'] as $i => $name) {
$moveFile($_FILES['application_files__certificates']['tmp_name'][$i],
$_FILES['application_files__certificates']['name'][$i],
$time);
$a_list[] = 'assets/siteContents/bewerbungen/'.$time.'_'.preg_replace('/[^a-zA-Z0-9\.]/s', '_',$_FILES['application_files__certificates']['name'][$i]);
}
}
If the error isn't caused by the special chars in the filename I am not sure what the problem might be.

Answer 1

The function returns FALSE on this conditions:
If filename is not a valid upload file, then no action will occur, and
move_uploaded_file() will return FALSE.
If filename is a valid upload file, but cannot be moved for some
reason, no action will occur, and move_uploaded_file() will return
FALSE. Additionally, a warning will be issued.
(Source: PHP.NET)
You are filtering your filename with this regex /[^a-zA-Z0-9\.]/s but this will only replace the first occurence of a special char not all.
Try adding the "g" modifier: /[^a-zA-Z0-9\.]/sg
Are you sure your client has the right permissions to move the file
to the desired location? I would double check them.