Handling 404 pages properly is essential for React applications to provide users with helpful feedback when they navigate to non-existent routes. As the creator of CoreUI, a widely used open-source UI library, I’ve implemented 404 handling in countless React applications and admin dashboards. From my experience with React, the most effective approach is to use a catch-all route with the wildcard path * at the end of your route definitions. This pattern ensures all unmatched routes display a user-friendly not found page.