Hello the same thing happens to me and I finished updating now and everything has fallen down, I am not an expert and I do not know what to do I can not enter anything.
Fatal error: Class ‘WP_Rest_Controller’ not found in /home4/macpelli/public_html/adonatolahiguera/wp-content/plugins/themeisle-companion/vendor/codeinwp/themeisle-content-forms/class-themeisle-content-forms-server.php on line 9