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If that does not work, you can attempt to clear credential caches and reactivate office 2016 for the Mac:
- Open finder > click → click go on the top menu bar> go to folder> input bar → go to folder → input the following path: ~/library/Group Containers/
- Right-click each of the folders below if present, and then click move to trash.
- ubf8t346g9.ms
- ubf8t346g9.office
- ubf8t346g9.officeosfwebhost
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