1. ssh to host
2. run sudo docker exec -it nextcloud sudo -u abc php /config/www/nextcloud/updater/updater.phar say yes to update say no to occ upgrade (will not work the default way) keep maintenance mode if ask
3. run sudo docker exec -it nextcloud sudo -u abc php /config/www/nextcloud/occ upgrade
4. run sudo docker exec -it nextcloud sudo -u abc php /config/www/nextcloud/occ maintenance:mode –off
5. connect to your nextcloud like you always do – done.