Installation of synapse not working

While installing synapse the installation process aborts with the following error

Waiting for activation of the extension object synapse: ....................................................ERROR
ERROR: Master did not mark the extension object active within 180 seconds.
Registering schema file activation failed: {u'mail': {u'cn=nextcloud,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=mattermost,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=msgpwl,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=self-service-passwordreset,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=msgpsi,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=msgpipsec,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=mswmi,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=msgpo,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=rocketchat,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=jitsimeet,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=univention-openvpn,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active', u'cn=63openvpn-sitetosite,cn=ldapacl,cn=univention,dc=360x,dc=media': u'active', u'cn=msprintconnectionpolicy,cn=ldapschema,cn=univention,dc=360x,dc=media': u'active'}} /usr/share/univention-appcenter/apps/synapse/synapse.schema failed
Aborting...

Any ideas what might be wrong?