[Samba] Migrating from Samba 3: no groups/users are imported ("listed, but then not found", "does not belong to our domain")

[Rowland Penny]

On Wed, 05 Sep 2018 15:26:30 +0700
Konstantin Boyandin via samba <samba at lists.samba.org> wrote:
> 
> Exactly that. I need to create a separate domain; after all the
> checks are done that switching to it works, the computers will rejoin
> the new domain. Our Samba 3 domain is used for years; since Window 10
> is unable to join it any more, we are finally migrating everything to
> Samba 4.

Then you might as well just provision a new domain, dump your users,
groups etc to a file. Write a script to parse the file and then add
them to your new AD.
 
> Note: every user belongs to "Domain Users" group, other group 
> memberships are lost.

Yes, every AD users primary group is Domain Users, your other problem
is very probably being caused by the way you are trying to bend the
classicupgrade upgrade script 

Rowland