During Exchange 2016 or Exchange 2013 server from one CU to another, you may run into strange set of errors.
Funny though, when you track those errors down you will probably end up removing OS patches and updates that actually needed and, even worse, that will not solve your issue.
I’m talkiing about tons of erros directly after the registry entries in the log file, something like:
Process execution failed with exit code 1072
Will, in my case, I had to do three things:
1. Re-confirm Schema, Forest, and Domain preparation is done using the “Setup” file from the CU I’m installing.
2. Un-install backup agent that is integrated with Exchange (in my case it was Veeam).
3. Run the setup time after time till it successfully completed. One server required (5) times, the other needed only (3).
Don’t forget to re-install the backup agent.