When I try to save as a ".docx" file, I get a KeyNotFoundException.
This may have to do with the way I'm trying to separate a file by section--maybe my code is wrong, but I've tried it 2 ways now: first, I created a new Document and added a section with Clone from the original. Then I loaded the original Document and Removed all sections except the one I want. The second way worked better for several reasons, but in both cases, I could only save to a ".doc" file. When I try a ".docx" file, I get a KeyNotFoundException.
I've uploaded my source code, but the original Word file is too big. I have posted it Google Drive at the link is included in a text file in the uploaded attachment.