OpenProject install/usage fatal errors

New tries - new failures!

Just installed a fresh UCS slave server in freshly upgraded UCS domain (all systems brought to version 4.4-3).
Trying to install OpenProject (it automatically selects version 10.3.0) and it fails miserably during installation:

with some error related to LDAP when trying to join the container system to the domain:
[LDAP Error: Type or value exists: krb5Key: value #2 provided more than once]

Configuring 4.3/openproject=10.3.0
Setting registry variables for openproject
Executing interface restore_data_before_setup for openproject
** Restore forced UCR layer:
** Restore ldap UCR layer
** Restore normal UCR layer:
Executing interface setup for openproject
Copying App Center's setup to container's /usr/share/univention-docker-container-mode/setup_custom
Joining
univention-join: joins a computer to an ucs domain
copyright (c) 2001-2019 Univention GmbH, Germany

Search DC Master:  done
Check DC Master:  done
Search ldap/base done
Search LDAP binddn  done
Join Computer Account: 

**************************************************************************
* Join failed!                                                           *
* Contact your system administrator                                      *
**************************************************************************
* Message:  Please visit https://help.univention.com/t/8842 for common problems during the join and how to fix them -- failed to modify Member Server cn=openp-84840293,cn=memberserver,cn=computers,dc=sih,dc=net [LDAP Error: Type or value exists: krb5Key: value #2 provided more than once]
**************************************************************************
Something went wrong while joining the system
Setup failed
Something went wrong while joining the system

appcenter.log

 27844 actions.install.progress         20-01-22 22:30:00 [   DEBUG]: 50
 27844 actions.install                  20-01-22 22:30:00 [    INFO]: Executing interface restore_data_before_setup for openproject
 27844 actions.install.container.1427   20-01-22 22:30:00 [   DEBUG]: Using container.1427 for container 1427d86ead6a44c4522ce5c2ca$
 27844 actions.install.container.1427   20-01-22 22:30:00 [   DEBUG]: Calling docker exec -u root 1427d86ead6a44c4522ce5c2ca73e540c$
 27844 actions.install.container.1427   20-01-22 22:30:01 [    INFO]: ** Restore forced UCR layer:
 27844 actions.install.container.1427   20-01-22 22:30:01 [    INFO]: ** Restore ldap UCR layer
 27844 actions.install.container.1427   20-01-22 22:30:01 [    INFO]: ** Restore normal UCR layer:
 27844 actions.install                  20-01-22 22:30:01 [    INFO]: Executing interface setup for openproject
 27844 actions.install                  20-01-22 22:30:01 [    INFO]: Copying App Center's setup to container's /usr/share/univenti$
 27844 actions.install.container.1427   20-01-22 22:30:01 [   DEBUG]: Using container.1427 for container 1427d86ead6a44c4522ce5c2ca$
 27844 actions.install.container.1427   20-01-22 22:30:01 [   DEBUG]: Calling docker exec -u root 1427d86ead6a44c4522ce5c2ca73e540c$
 27844 actions.install.container.1427   20-01-22 22:30:01 [    INFO]: Joining
 27844 actions.install.container.1427   20-01-22 22:30:02 [    INFO]: univention-join: joins a computer to an ucs domain
 27844 actions.install.container.1427   20-01-22 22:30:02 [    INFO]: copyright (c) 2001-2019 Univention GmbH, Germany
 27844 actions.install.container.1427   20-01-22 22:30:02 [    INFO]:
 27844 actions.install.container.1427   20-01-22 22:30:03 [    INFO]: Search DC Master:  done
 27844 actions.install.container.1427   20-01-22 22:30:09 [    INFO]: Check DC Master:  done
 27844 actions.install.container.1427   20-01-22 22:30:49 [    INFO]: Search ldap/base done
 27844 actions.install.container.1427   20-01-22 22:30:51 [    INFO]: Search LDAP binddn  done
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]: Join Computer Account:
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]:
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]: *************************************************************$
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]: * Join failed!                                               $
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]: * Contact your system administrator                          $
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]: *************************************************************$
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]: * Message:  Please visit https://help.univention.com/t/8842 f$
 27844 actions.install.container.1427   20-01-22 22:30:54 [    INFO]: *************************************************************$
 27844 actions.install.container.1427   20-01-22 22:30:54 [ WARNING]: Something went wrong while joining the system
 27844 actions.install.container.1427   20-01-22 22:30:54 [ WARNING]: Setup failed
 27844 actions.install.container.1427   20-01-22 22:30:54 [CRITICAL]: Something went wrong while joining the system

 27844 actions.install.container.1427   20-01-22 22:30:54 [CRITICAL]: Setup failed

Any idea on what to check/do??
Are those strange issues happening only to me?? Am I doing something wrong?? As this is all “fresh install”… so I simply cannot understand WHY are the so many (at least for me) problems installing OpenProject (and other apps)…

Any hints appreciated!

Regards