I encountered this error using Office 2016 (32-bit) on Windows 7 x64. Logged on to the system as a User, I opened Control Panel>Mail>Data Files and attempted to add a new data file under my default Exchange account. All efforts led to the Error code: 0x8000ffff.
This error apparently occurs due to the path I took to add the new data file. To successfully add a new data file use this:
Open Outlook 2016
Click File>Account Settings (big button to the right)>when it drops down click Account Settings.
This will open the Account Settings for the account in the same view as going through the Control Panel, except now a data file can be added without error.
Click Data Files tab>Add>Select the location for the file, and type the name in the box>Click OK.
The file should successfully be added this time.