Hi Nino,
we're facing the same problems reported back in August on a German Exchange 2016 installation.
In the setup log files at C:\Program Files\Microsoft\Exchange Server\V15\Logging\Update\msi\ExchangeUpdate-....log we found the following entry:
ExecSecureObjects: Error 0x80070534: failed to get sid for account: Network Service
Is this really the same issue like in August? We have not used the temporary workaround mentioned in august (manually creating a user named "Network Service"). Do folks who have successfully installed the October update on a German system still have the manually created account?
Regards,
Dennis