This is due to the office excel registry being corrupted where it will need to be recreated to resolve to do so:
-Open or type Regedit (the user needs to put in their pw as this will not work otherwise)
-Go to the following location: \HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Excel
and change the Excel entry to Excel.old
In some case, you may need to change the follow location in addition or if you're not able to change the original.
\HKEY_CURRENT_USER\Software\Microsoft\Office\Excel