Problem: Horde Login is not possible for any user
Your users can not use Horde any more while send and receive of emails through a mailclient (ie Thunderbird) works.
When checking the Horde access through
univention-app shell horde univention-ldapsearch uid=Administrator
you are not getting any result:
During the scheduled password change of the app itself there is an issue which causes a wrong password and therefore not connection to ldap. A Bug exists and as a workaround you should write the password as follows:
univention-app shell horde ucr commit /etc/horde/horde/conf.d/10-ucs.php