The answer to 'why is my stone walkway bare spots' is that there are several common causes, including lack of soil preparation, improper stone installation, and natural weathering. Bare spots can develop over time as the stones shift, settle, or become dislodged. Symptoms include uneven surfaces, gaps between stones, and exposed dirt or grass growing through.
To fix bare spots, you'll need to assess the underlying cause. For minor issues, you may be able to DIY by resetting or replacing individual stones. But for more significant problems, it's best to call a professional landscaper to properly re-lay the walkway and ensure it's stable and level.