Solution
set redis password, described in
https://help.nextcloud.com/t/solved-latest-docker-image-broke-the-installation-redis-password-auth/87598/2
docker-compose -f docker-compose.yml build --pull
docker-compose -f docker-compose.yml up -d
docker exec -it -u www-data <nextcloud-container> /bin/bash
./occ upgrade
throws error in “news” app:
Update app news from appstore
An unhandled exception has been thrown:
Error: Undefined class constant 'DEFAULT_SETTINGS' in /var/www/html/custom_apps/news/lib/Migration/MigrateConfig.php:49
try again
./occ upgrade
(works this time?? - well)
./occ maintenance:mode --off