When GitHub Pages displays a 404 error, it typically indicates a misconfiguration, such as an incorrect branch selection or a missing index.html in the repository’s root. Start by confirming the branch and directory settings under *Settings > Pages*, ensuring the selected branch contains the source files for your website, typically in a dedicated folder or at the root level. For static sites, an index.html file should be present at the root. If using a custom domain, check DNS settings to confirm they point correctly to GitHub Pages. Double-checking these setup elements usually resolves the 404 error, allowing GitHub Pages to display the intended content.