Error when I upgrade to catch everest pro

Hi, can you please advise why I get this message. It says upload successful but when I go to activate I receive this message. Fatal error: Call to undefined function wp_get_theme() in /home/kiss2137/public_html/wp-content/themes/catch-everest-pro-1/update_notifier.php on line 13 my website www.kissthegroom.com.au Look forward to your reply. Cheers Lisa