Fatal error: Uncaught Error: Call to undefined function add_shortcode() in /opt/app-root/src/wp-content/plugins/jetpack/modules/shortcodes/mailchimp.php:20 Stack trace: #0 /opt/app-root/src/wp-content/plugins/jetpack/modules/shortcodes/mailchimp.php(39): jetpack_mailchimp_subscriber_popup() #1 {main} thrown in /opt/app-root/src/wp-content/plugins/jetpack/modules/shortcodes/mailchimp.php on line 20