I have a system with a DC Master and a DC Slave installed. Windows computers join the domain of the DC Slave and the information synchronizes with the DC Master. The problem is that I an S4 reject for each computer that joins the domain:

# univention-s4connector-list-rejected

UCS rejected


S4 rejected

    1:    S4 DN: DC=IDGTRM5131,DC=idicat.net,CN=MicrosoftDNS,DC=DomainDnsZones,DC=idicat,DC=net
         UCS DN: <not found>
    2:    S4 DN: DC=31.151,DC=80.10.in-addr.arpa,CN=MicrosoftDNS,DC=DomainDnsZones,DC=idicat,DC=net
         UCS DN: <not found>
    3:    S4 DN: DC=IDGTRM5123,DC=idicat.net,CN=MicrosoftDNS,DC=DomainDnsZones,DC=idicat,DC=net
         UCS DN: <not found>
    4:    S4 DN: DC=23.151,DC=80.10.in-addr.arpa,CN=MicrosoftDNS,DC=DomainDnsZones,DC=idicat,DC=net
         UCS DN: <not found>

And when I go to the s4-connector log on /var/log/univention/connector-s4.log, the error that it gets is:

29.12.2016 22:12:37,544 LDAP        (ERROR  ): unexpected Error during s4.resync_rejected
29.12.2016 22:12:37,545 LDAP        (ERROR  ): Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/univention/s4connector/s4/__init__.py", line 2120, in resync_rejected
    mapped_object = self._object_mapping(property_key, object)
  File "/usr/lib/pymodules/python2.7/univention/s4connector/__init__.py", line 1764, in _object_mapping
    object = function(self, object, dn_mapping_stored, isUCSobject=(object_type == 'ucs'))
  File "/usr/lib/pymodules/python2.7/univention/s4connector/s4/dns.py", line 309, in dns_dn_mapping
    s4connector.lo_s4.lo.search_ext_s(univention.s4connector.s4.compatible_modstring(search_dn), ldap.SCOPE_BASE, s4_RR_filter, [s4_RR_attr])[0][1][s4_RR_attr][0])
KeyError: 'dc'


I searched on the code and placed a debug statement that prints the line that gives the error:

univention.s4connector.s4.compatible_modstring(search_dn), ldap.SCOPE_BASE, s4_RR_filter, [s4_RR_attr])[0][1][s4_RR_attr][0]

And what I got was:

 [('DC=36.151,DC=80.10.in-addr.arpa,CN=MicrosoftDNS,DC=DomainDnsZones,DC=idicat,DC=net', {'DC': ['36.151']})]

So, the error appears because it tries to find the key 'dc' in this dictionary:

{'DC': ['36.151']}

But the only key that exists there is 'DC', uppercase. The dn DC=36.151,DC=80.10.in-addr.arpa,CN=MicrosoftDNS,DC=DomainDnsZones,DC=idicat,DC=net is generated by the connector, so I don't know if there's a parameter or something that can be tuned in order to tell it to generate it in lowercase letters.