demote error

[Daniele Dario]

Hi samba team,
I've seen in other threads that with Version 4.0.0alpha20-GIT-81d1749
replication of DNS partitions between DCs now should be automatic so I
decided to try to demote my secondary DC to try to join it again to the
domain and see if replication starts also for me.

Trying to run samba-tool domain demote -d 10 it fails with

...
../librpc/rpc/dcerpc_util.c:140: auth_pad_length 12
     drsuapi_DsReplicaSync: struct drsuapi_DsReplicaSync
        out: struct drsuapi_DsReplicaSync
            result                   : WERR_OK
rpc reply data:
[0000] 00 00 00 00                                       .... 
lpcfg_servicenumber: couldn't find ldb
added interface eth0 ip=fe80::20e:cff:fe3c:b729%eth0
bcast=fe80::ffff:ffff:ffff:ffff%eth0 netmask=ffff:ffff:ffff:ffff::
added interface eth0 ip=192.168.12.2 bcast=192.168.12.255
netmask=255.255.255.0
added interface eth0 ip=fe80::20e:cff:fe3c:b729%eth0
bcast=fe80::ffff:ffff:ffff:ffff%eth0 netmask=ffff:ffff:ffff:ffff::
added interface eth0 ip=192.168.12.2 bcast=192.168.12.255
netmask=255.255.255.0
Changing userControl and container
Error while demoting, re-enabling inbound replication
ldb:acl_modify: options
Sorting rpmd with attid exception 3 rDN=CN DN=CN=NTDS
Settings,CN=KDC02,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=saitelitalia,DC=local
ERROR(ldb): Error while changing account control - LDAP error 1
LDAP_OPERATIONS_ERROR -  <00002020: Operation unavailable without
authentication> <>
  File
"/usr/local/samba/lib/python2.7/site-packages/samba/netcmd/domain.py",
line 288, in run
    attrs=["userAccountControl"])

how can I proceed to solve the problem?

Thanks in advance,
Daniele