Is your form your sending from properly configured ?
Your form must be multipart/form-data
<form action="upload.php" method="post" enctype="multipart/form-data">
Thanks for this website I visit it often.
The following page will need to be updated saying: PHP 4+ - PHP 7.2 about its versions
The each() function is deprecated in PHP7.3
https://www.w3schools.com/PHP/func_array_each.asp