When I tried to open my merge_fields CSV file into Microsoft Word’s Mail Merge Manager, Word crashed or gave an error.
The format of the CSV file is different to what Word expects. A common cause is that it contains special characters. Those can be introduced when a CSV file is edited and saved in Microsoft Excel. They normally don’t appear when you look inside the CSV file.
Re-export the merge_fields CSV file from your template’s view page. The CSV will then be correctly formatted.
If you need to edit the merge_fields CSV file then use a text editor (like WordPad or Notepad) instead of Microsoft Excel.