To resolve the 'Word cannot open the existing file (Normal.dotm)' error, reset the Normal.dotm file, use Open and Repair, and disable add-ins.

Cluttered User Interface Word has a lot of features that you're not going to use, and they tend to clutter the interface. This can make Word confusing and overwhelming, especially for new users.

If you see Error Bookmark Not defined or Error Reference source not found in Word, then use the solutions mentioned in this post to fix the issue.