Undefined function wp_get_theme (

Dear,

I’ve installed the wordpress, so I chose carton theme. But now the following message appears on my website: “Fatal error: Call to undefined function wp_get_theme () in / home/deafc569/public_html/wp-content/themes/carton/functions.php on line 7,” but have you tried to get CPanel and mo clicked “File Manager”, but does not appear codes and I do not understand the reason for the error message.

Please help me. I’m waiting.

Best Regards,

Joaquim Amado