[Samba] Trouble during classicupgrade

[Andreas Heinlein]

Hello,

I just wanted to say that after some hours of digging, I found the
problem. It turned out to be quite trivial...

The winbind package was missing on that machine. This is a separate
package in Debian; after installing it everything seems to work.

There were two factors that led me to remove winbind at first:
1. The wiki says "Configuring Winbindd on a Samba AD DC - Only required
if using the DC as a file server". That is misleading, obviously
winbindd itself is actually required.
2. The Debian winbind package has a weird bug that causes it to
unconditionally try to start winbindd as a standalone service even on a
samba AD DC (https://bugs.debian.org/863285), which obviously fails. I
came across that error, tried to start winbindd manually and got a
message explaining "server role = 'active directory domain controller'
not compatible with running the winbindd binary. You should start
'samba' instead, and it will control starting the internal AD DC
winbindd implementation, which is not the same as this one." That too
led me to the assumption that a separate winbind package is now no
longer needed and I could remove it.

Only after looking through the logs again, I found the message that
samba failed to start /usr/sbin/winbindd, which is in the winbind package.

So the actual problem is now gone, but maybe someone wants to look into
these potentially misleading messages.

Thank you for your help!

Andreas