In the official documentation for the DC samba update, it is written that the domain should work after the update ... In practice, the domain is lost ... Cut from the official doc:
Stop all Samba services.
Install the latest packages over your existing ones.
Start the samba daemon.
Run the Samba AD DC database check to identify (and fix) any potential problems with the database.
Check your Samba log files for errors.
Test the Samba services work on your updated installation, e.g. verify users can login successfully via the upgraded DC.
The last point of the instruction does not work ...