~/Library/Group Containers/UBF8T346G9.Office/User Content.localized/Startup.localized/Word

Just delete the file below this one. You can refer to the following solution.

I had the same problem, and found that it was due to incompatible Adobe Add-in “linkCreation.dotm”.

It is located at:
~/Library/Group Containers/UBF8T346G9.Office/User Content.localized/Startup.localized/Word
Once you remove the file and re-start Word, no more errors.