No horde login: Missing required connection parameters

Two servers, a slave DC hosts a mail system with horde. After the latest reboot Horde somehow didn’t allow a login. It said “E-Mail server temporarily unavailable”. I checked the app settings and found out that somehow the master DC was set as the E-Mail server. I changed it back to the slave server as expected. When I now log in I get:

Ein schwerer Fehler ist aufgetreten:

Missing required connection parameter(s).

Details wurden für den Administrator mitgeloggt.

I tried:

univention-app shell horde /usr/share/univention-mail-horde/univention-mail-horde-login-wrapper <username>

This returned the correct e-mail address for <username>.

Calendar does not work either, mail works with external clients.

Any ideas on this one ?

Thanks - Martin

Found it by myself:

Missing required connection parameter(s) suggests a problem with the notes (Mnemo) function. Since I do not use that I disabled it by:

univention-app shell horde ucr set horde/mnemo/status='inactive'

Hope this helps others - Martin