[Samba] accidentally upgraded DC to 4.17.3 ... didn't work

[Michael Tokarev]

23.11.2022 11:59, Stefan G. Weichinger via samba wrote:
..
> Ad my "reinstall approach": I tend to be rather defensive on a productive DC like this one. So deleting samba-related files etc is something I avoid 
> ... -> I would need a definitive howto for this, because I know too little about the details. I don't want to corrupt any AD-related information etc
> 
> Maybe the change from the Louis-packages to the backports-packages and/or 4.16 -> 4.17 left some wrong packages behind or so.

A package manager (dpkg in this case) ensures all the installed binaries
(and other files) are exactly the same whenever you install fresh or
upgrade or even downgrade. Louis repository is based on Debian packages,
it is not different from regular debian samba packages. Even if it did,
it doesn't really matter.

What *does* matter is the content of /var/lib/samba/.  *This* is where
all the issues happens, *especially* issues due to incompatibilities
or past wrong settings or whatnot.

And this is the place which is not covered by the package manager,
because it is local state data, it is not a package manager business
to mess with these.

So it doesn't matter how you ended up with a given set of binaries, -
it should be the same set, belonging to this version of the packages
you installed, nothing else.  But it does matter which state data
do you have.

It is the upgrade of the state data (mostly in /var/lib/samba/) which
breaks stuff at upgrades (when it breaks).  And it is the reason why
people demote a DC, remove a server from domain, and re-join it -
to get fresh /var/lib/samba/* without prior (mis)configurations,
failures during upgrades, or whatever else. It is the only thing
which actually matters, - the local state.

You don't need to reinstall binary packages, - you'll end up with
exactly the same files from exactly the same packages. But you
can't have the same freshly created correct state data unless you
remove the old, non-working, data and generate the right one.
This can't be done without removing old data first.

That's basically it.

> I still have 2 servers to upgrade there, so I am open to suggestions (and thankful if they work ;-) ).

FWIW, I don't see anything between 4.16 and 4.17 which can break
in this context. Re-joining is actually a simple and stright-forward
procedure, so for a quick fix it is always available.

I can't say more at this time, unfortunately, - today was a very
busy day for me too.

Thanks,

/mjt