You get the error in the template manager when trying to add a new Worddocument, “Could not add %1 to the database” And in details you can find “Incompatible file type and file extension”

If in Word you have “File→option→ save→” chosen doc instead of docx then you will get an error in the template manager, when creating a new template.

The solution is to change the “save file in this format” to docx.