reserialize.php

<?php
global $wpdb;
$files = $wpdb->get_var("select meta_value from {$wpdb->prefix}postmeta where meta_key = '__wpdm_files' and post_id = '{$package['ID']}'");
preg_match_all("/i\:([0-9]+)/", $files, $matches);
$find = $matches[0];
$replace = [];
foreach($matches[1] as $index) {
	$replace[] = "s:".strlen($index).':"'.$index.'"';
}
$files = str_replace($find, $replace, $files);

$files = $package['files'] = unserialize($files);