thanks for the hint but this does not seem to be the error, occ status provides the right version information
root@ubuntu-nc:/var/www/nextcloud# sudo -u www-data php /var/www/nextcloud/occ status
- installed: true
- version: 19.0.12.0
- versionstring: 19.0.12
- edition:
more like this, but sadly there isnt a real solution in this thread:
updater version v19.0.3-8-gbfdc40b is the same. manually check with occ also return nothing:
root@ubuntu-nc:/var/www/nextcloud# sudo -u www-data php /var/www/nextcloud/occ update:check
Everything up to date