A 404 means your server is working, but there's nothing at that address. The page was deleted, moved, renamed, or the link pointing to it is wrong. If one page is missing, fix the link or add a redirect from the old address to the new one. If your whole site suddenly shows 404s, something bigger changed: a migration, a routing setting, or the site's files are missing.
What's the problem
Visitors see "404 Not Found" or "Page not found". It might be one old link, every page except the homepage, or images and files rather than pages.
Why it happens
- The page was deleted or its address changed, and old links still point to it.
- A typo in a link, menu or ad.
- The site was migrated or rebuilt and the URLs changed without redirects.
- Every page except the homepage 404s: usually the server's URL rewriting isn't set up. On WordPress, the permalinks need saving again. On single-page apps (React, Vue), the host needs to send all routes to
index.html. - Files are missing after a deploy, or are in a different folder than the code expects.
- Case sensitivity:
/Aboutand/aboutare different addresses on most servers.
How to fix it
- Check the exact URL that 404s. Compare it with where the page really is.
- For moved pages, add a permanent (301) redirect from the old address to the new one, so links and search rankings carry over.
- If all inner pages 404: on WordPress, go to Settings → Permalinks and click Save. On a single-page app, add the host's "rewrite all to index.html" rule.
- If files 404 after a deploy, check the build output actually includes them and the paths match.
- Make your 404 page helpful: a search box and links to the main pages.
What Preventionlabs checks
One click runs the full report on your domain. For this problem it shows up to 50 pages from your sitemap, listing any that fail or are slow, plus broken links on them; whether missing pages return a real 404. With Cloudflare connected, it also shows which pages returned server errors (5xx) to visitors, and when; recent deploys and account changes, with their times.
Run your free reportYour first report is free, no card needed. Then A$50 a month, up to 10 domains. Read-only: it never changes anything.
Sources
- MDN Web Docs: 404 Not Foundreference
The HTTP 404 Not Found client error response status code indicates that the server cannot find the requested resource.
- WordPress: Customize permalinksofficial docs
On the WordPress dashboard, go to Settings → Permalinks Screen.