I was using WPMU

Hello,
I was using WPMU DEV to update our site yesterday. It has since been giving this error message below
Warning: require_once(/home/admin4ima/mentoringassociation.org/wp-content/themes/sento/admin/main/customizer_migration_notice/customizer_migration_notice.php): failed to open stream: No such file or directory in /home/admin4ima/mentoringassociation.org/wp-content/themes/sento/functions.php on line 22

Fatal error: require_once(): Failed opening required '/home/admin4ima/mentoringassociation.org/wp-content/themes/sento/admin/main/customizer_migration_notice/customizer_migration_notice.php' (include_path='.usr/local/lib/phpusr/local/php5/lib/pear') in /home/admin4ima/mentoringassociation.org/wp-content/themes/sento/functions.php on line 22

Please help as I can't even see the dashboard anymore.