REL-002
Missing custom 404 page
MediumDefault severity · Reliability · SEO, quality and performance
Last reviewed
What it checks
Requests a URL that cannot exist and inspects the status code and page.
Why it matters
Returning 200 for missing pages (a “soft 404”) confuses search engines and monitoring; a bare default page loses the visitor.
Recommended fix
Return a real 404 status with a branded page that links back to the homepage.
How to verify
Visit /this-page-does-not-exist and confirm the custom page shows and DevTools reports status 404.
Example fix prompt
Generic prompt (your report adds the evidence)
Please fix this production issue in my app.
Issue REL-002: Missing custom 404 page
Site: https://your-app.example
First confirm the issue in the code or live config. If it is not present, say so and change nothing.
Task: Add a custom not-found page that matches the site design, links back to the homepage and main sections, and make sure unknown URLs return HTTP status 404 (for single-page apps, configure the host so unknown routes return 404 instead of 200).
Constraints: make the smallest change that fixes this, keep the current design and behaviour, never paste secret values into code or chat, and tell me which files you changed.
Done when: Visit /this-page-does-not-exist and confirm the custom page shows and DevTools reports status 404.