A family of Microsoft word processing software products for creating web, email, and print documents.
I came across this problem earlier today when working with a client machine that wanted to open documents from her mails but needed to go download and manually open them, digging around I found the same fault as listed above. I tried finding a solution online and everyone pointed me towards doing either an update or rollback to get it working (safe mode never worked)
After doing both of the above it still gave me the same problem so I instead followed the link provided and did the following
-First, go into settings and make sure regional and language settings are correct
-Reopen word so that the same error occurs and close word again.
-Search in the spotlight for Normal.dotm (I found multiple entries, others will have normal.dotm-{numbercombination} )
-Delete every normal.dotm file I can find but leave 1 of the normal.dotm files with the number combination and rename it to Normal.dotm
Reopen word and no more error
^if this is confusing follow the link: https://support.office.com/en-us/article/recover-your-default-template-a85ad0e7-d067-49c8-9692-7db95a87ae47?ui=en-US&rs=en-US&ad=US
Best of luck and hope this helps the way it helped me