When CPUU is run on a machine with the Outlook 2016 client, it immediately fails and the following error is written to the CPUU log file:
This error can occur if the following registry key is missing on the machine where CPUU is being run: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover\
When Outlook 2016 is installed and launched for the first time on a system, the above registry key is created (at the Welcome screen). In some environments this key may not be present for some reason, however CPUU will fail as it expects this Autodiscover key to be present.
To resolve this issue the HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover\ key must be created, either manually, via Group Policy, or the following line can be added to the beginning of the CPUU batch (.bat) file:
REG ADD HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\AutoDiscover