Problem:
Cannot upgrade to UCS5.0-6 with kopano installed. After the upgrade Kopno is not working anymore.
Solution:
univention-upgrade --ignoressh --ignoreterm --noninteractive --disable-app-updates
univention-upgrade --ignoressh --ignoreterm
→ Kopano Core: Version 8.7.25.0-1 can be upgraded to 8.7.25.0-2
univention-install php7.3
a2enmod php7.3
ln -s /etc/php/7.3/mods-available/kopano.ini /etc/php/7.3/apache2/conf.d/
service apache2 reload
Maybe also the variable mail_postfix_ldap_timeout needs to be set