Problem with installing theme – Serialize.php

Hello,

When I try to install a theme on a shared web hosting I get this error:

PHP Fatal error: require_once(): Failed opening required ‘System.php’ (include_path=’.:’) in /var/www/vhosts/thoril.com/httpdocs/wp/wp-content/themes/funding_press/funding/lib/PayPal/Serializer/Serializer.php on line 54, referer: http://thoril.com/wp/wp-admin/update.php?action=upload-theme

What should I do?

Kind regards