How can I debug a 404 error on GitHub Pages React application?

Debugging a 404 error involves several steps. First, use your browser's developer tools (Network tab) to examine the request and response headers. This can help determine if the server is responding with a 404 error and what the specific URL is. Secondly, try accessing the URL directly from your local machine using `npm start` or `yarn start` to confirm that your React application is building and running correctly. Inspect your `package.json` and `build` scripts for any errors.