Custom 404 page
Also known as 404 error page · Not Found page
A branded, helpful page served for unknown URLs that also returns the correct HTTP 404 status so crawlers know the resource does not exist.
What it is
When a requested URL has no matching resource, the server should respond with HTTP 404 (or 410) and render an error page. A custom 404 replaces the bare default with branded navigation, search, and links back to useful content.
Why it matters
If missing pages return 200 instead of 404, search engines treat them as real, valid pages, wasting crawl budget and creating soft-404 and index-bloat problems. A correct 404 status keeps crawlers and AI agents from indexing or citing dead URLs, while a helpful page recovers lost visitors.
How to verify
Request a deliberately nonexistent URL and check the response status in DevTools Network tab or with curl -I, expecting 404, not 200. Google Search Console's Pages report and the URL Inspection tool also surface soft 404s where the status and content disagree.
How to fix
Configure the server or framework to return a genuine 404 status for unmatched routes and render a branded page with a clear message, search, and links to key sections. Do not redirect all unknown URLs to the homepage, as that creates soft 404s; use 301 redirects only for URLs that genuinely moved.
Related terms
- Sampled Internal Links OKA representative sample of internal links resolves with HTTP 200 rather than 404 or other errors.
- noindex TagA directive, set via meta tag or HTTP header, that tells search engines to keep a page out of their index.
- XML SitemapAn XML file listing a site's canonical URLs to help search engines discover and prioritize pages for crawling.
- robots.txtA plain-text file at the site root that tells crawlers which paths they may or may not request.
Official references
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