Solved.
The app was not “registered” in the AppStore after the upgrade to UCS 4.2 (missing “Installations” entry):
# univention-app list | grep -A3 kopano
kopano-core
Name: Kopano Core
Latest version: 8.3.1.32
Installations:
--
kopano-webapp
Name: Kopano WebApp
Latest version: 3.3.0.610
Installations: host.xyz.com
--
kopano-webmeetings
Name: Kopano WebMeetings
Latest version: 3.0.0.92
Installations:
--
z-push-kopano
Name: Z-Push for Kopano
Latest version: 2.3.7
Installations: host.xyz.com
You can register the app by the following command:
# univention-app register kopano-core
Jürgen.