[Samba] Clussicupgrade tdbsam Unable to load modules for /var/lib/samba/private/secrets.ldb

[basti]

Hello,

i try to upgrade a NT4-PDC to AD.

OS: Debian 10.1
Samba: 4.9.5-Debian

read
https://wiki.samba.org/index.php/Migrating_a_Samba_NT4_Domain_to_Samba_AD_(Classic_Upgrade)

scp -r /var/lib/samba/private/ /var/lib/samba/samba3tdb/
scp /etc/samba/smb.conf /var/lib/samba/samba3tdb/

samba-tool domain classicupgrade --dbdir=/var/lib/samba/samba3tdb/
--realm=samdom.example.com --dns-backend=BIND9_DLZ
/var/lib/samba/samba3tdb/smb.conf

Setting up secrets.ldb
WARNING: Module [samba_secrets] not found - do you need to set
LDB_MODULES_PATH?
Unable to load modules for /var/lib/samba/private/secrets.ldb: (null)
ERROR(ldb): uncaught exception - None
  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.py", line
1681, in run
    useeadb=eadb, dns_backend=dns_backend, use_ntvfs=use_ntvfs)
  File "/usr/lib/python2.7/dist-packages/samba/upgrade.py", line 738, in
upgrade_from_samba3
    use_ntvfs=use_ntvfs, skip_sysvolacl=True)
  File "/usr/lib/python2.7/dist-packages/samba/provision/__init__.py",
line 2262, in provision
    backend_credentials=provision_backend.credentials, lp=lp)
  File "/usr/lib/python2.7/dist-packages/samba/provision/__init__.py",
line 1015, in setup_secretsdb
    secrets_ldb = Ldb(path, session_info=session_info, lp=lp)
  File "/usr/lib/python2.7/dist-packages/samba/__init__.py", line 115,
in __init__
    self.connect(url, flags, options)