Error "Unable to create the deduplication storage"
An Application Event Logs error, Event ID 1026 reports additional information;
Event ID : 1026
Windows cannot load the user's profile but has logged you on with the default profile for the system. DETAIL - The system cannot find the file specified.
The same error can be seen when logged in using the Local Admin account.
This is due to an issue with the user profile, where the customer does not have the permission to install.
Delete the default user profile, which the customer is using.
Create a new profile and attempt to configure the deduplication storage, which should now work.