[Samba] passdb.error: uncaught exception - requested file lock

[Mario Codeniera]

Hi

Can someone give insights please on this issue or solution...
...
Importing users
ERROR(<class 'passdb.error'>): uncaught exception - Unable to add sam
account 'mmcarter', (-1073741739,A requested file lock cannot be granted
due to other existing locks.)
  File "/usr/lib64/python2.7/site-packages/samba/netcmd/__init__.py", line
176, in _run
    return self.run(*args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/samba/netcmd/domain.py", line
1636, in run
    useeadb=eadb, dns_backend=dns_backend, use_ntvfs=use_ntvfs)
  File "/usr/lib64/python2.7/site-packages/samba/upgrade.py", line 803, in
upgrade_from_samba3
    s4_passdb.add_sam_account(userdata[username])
ldb: A transaction is still active in ldb context [0x555d563d0180] on
/var/lib/samba/private/sam.ldb

Background:
I tried to upgrade our existing server using classicupgrade previously
working before with the previous version but because it was pending in a
couple of months as working with other projects.
Currently using with Samba 4.8.3 in Fedora 28, I don't know if it relates
to the previous version (4.7.x, which I used before) as I upgrade the
distro. I tried to delete the said account, then another account or machine
will appear with the same error up to 10 tries, I stop as kept appearing.

As Fedora 28 don't have samba 4.7.x version, will try to recreate the
server on a separate machine if this will resolve the issue.

Thanks.