[Samba] Kerberos fails in some cases

[Sergio Belkin]

Hi folks,
I can use kerberos to create or delete user, eg:

samba-tool user create test -k yes

however, if I want to perform a backup it fails:

samba-tool domain backup online --targetdir=/srv/backup
--server=192.168.50.40 -k yes
gensec_spnego_create_negTokenInit_step: Failed to setup SPNEGO negTokenInit
request
Failed to bind - LDAP client internal error: NT_STATUS_INVALID_PARAMETER
Failed to connect to 'ldap://192.168.50.40' with backend 'ldap': LDAP
client internal error: NT_STATUS_INVALID_PARAMETER
ERROR(ldb): uncaught exception - LDAP client internal error:
NT_STATUS_INVALID_PARAMETER
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/__init__.py", line
177, in _run
    return self.run(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/domain_backup.py",
line 228, in run
    dns_backend='SAMBA_INTERNAL', targetdir=tmpdir)
  File "/usr/lib/python2.7/dist-packages/samba/join.py", line 1509, in
join_clone
    include_secrets=include_secrets)
  File "/usr/lib/python2.7/dist-packages/samba/join.py", line 1584, in
__init__
    dns_backend=dns_backend)
  File "/usr/lib/python2.7/dist-packages/samba/join.py", line 98, in
__init__
    credentials=ctx.creds, lp=ctx.lp)
  File "/usr/lib/python2.7/dist-packages/samba/samdb.py", line 64, in
__init__
    options=options)
  File "/usr/lib/python2.7/dist-packages/samba/__init__.py", line 115, in
__init__
    self.connect(url, flags, options)
  File "/usr/lib/python2.7/dist-packages/samba/samdb.py", line 79, in
connect
    options=options)

What could be wrong?

I use samba 4.9.3 on Debian (Van Belle repo)

Thanks in advance!

-- 
--
Sergio Belkin
LPIC-2 Certified - http://www.lpi.org