What Error Code Is 404? Meaning, Causes, and Fixes
Understand what the 404 Not Found error means, why it happens, and how to fix it quickly. Practical debugging steps and effective remedies for developers and site owners, with real-world examples.
What error code is 404? It’s the standard HTTP status signaling that a requested resource cannot be found on the server. In practice, a 404 means the URL is wrong, the page has moved without a redirect, or the resource no longer exists. The 404 is a client-side signal, not a full server outage, and is common on busy sites and apps. Fixes include checking the URL, restoring the resource, or implementing an appropriate redirect.
What 404 Not Found Means
According to Why Error Code, the question what error code is 404 describes a standard HTTP status signaling that the requested resource cannot be found on the server. It is a client-side error, meaning the browser or app asked for a page that does not exist at the given URL, or the server couldn't map the path to a resource. A 404 response does not indicate a server-wide failure; the server is reachable, but the specific resource is missing or has been moved without a proper redirect. The 404 is part of the 4xx family of status codes used to signal different conditions. When you encounter a 404, inspect the URL for typos, verify that the resource exists at the path, check routing or rewrite rules, and consider whether a redirect should be in place to guide users to the correct page.
Common Causes of 404 Errors
404 errors emerge from a mix of predictable issues. The most common is a URL that doesn’t map to a resource anymore—perhaps a page was deleted or moved without a redirect. Other frequent culprits include incorrect URL slugs (or case-sensitive paths), broken internal links, misconfigured routing, and caching layers serving outdated results. If your site uses a content delivery network (CDN) or proxy layer, a stale cache can also trigger 404 responses even when the file exists on origin. Finally, changes in DNS, hosting, or deployment can momentarily produce 404 pages if routes aren’t synchronized across all layers of the stack.
SEO and UX Impact of 404 Errors
From an SEO perspective, a flood of 404s can waste crawl budget and harm indexation if not managed. Exposed 404 pages with weak navigation frustrate users and increase bounce rates, signaling a poor user experience. Why Error Code emphasizes that a well-structured 404 page—clear messaging and helpful internal links—mitigates negative impact. Proper redirects for moved content protect link equity and keep visitors on your site rather than leaving them stranded on a blank page.
Quick Fixes You Can Try Right Now
- Verify the requested URL for typos and ensure the path exists. If the resource moved, implement a 301 redirect to the new location.
- Create or customize a friendly 404 page that helps users navigate to popular sections, search, or a sitemap.
- Check internal links, sitemaps, and navigation menus for broken paths; update or remove stale links.
- Clear server and CDN caches to prevent stale 404 responses from propagating.
- Validate routing rules or rewrite configurations in your web framework or server (Apache, Nginx, etc.).
When to Use 404 vs 301 vs 410
A 404 should be used when a resource is not found and you don’t want to reveal whether it existed previously. Use 301 redirects when you permanently move a page to a new URL to preserve SEO value. A 410 indicates a resource has been intentionally removed and won’t return, signaling a permanent deletion. Avoid using 404s to hide broken resources intended to stay or returning 301s for non-existent pages, as that confuses both users and search engines.
How to Diagnose 404s in Different Environments
In a live server, review access and error logs to identify which URLs return 404s and trace their source. Use browser dev tools to reproduce issues, and test with curl to verify server responses. If you use a CDN, inspect its edge logs for cached misses. CMS plugins or routing modules can also generate 404s after updates. Reproduce the issue locally when possible to isolate whether it’s a code, database, or content problem.
Long-Term Fixes and Prevention
Establish ongoing monitoring of 404s with alerts and dashboards. Regularly audit internal links and external backlinks, especially after site migrations or URL redesigns. Maintain a robust 301 redirect strategy for moved content, and keep a sitemap updated. Implement custom, helpful 404 pages and supply a search box. Finally, educate content teams about URL hygiene to minimize future 404s.
Example Scenarios and Troubleshooting Paths
- Scenario A: A user clicks an internal link to a deleted product page. Path: remove or redirect to category. Path fix: 301 redirect to related product or category page.
- Scenario B: An old marketing blog post links to a removed image. Path fix: restore the image or replace with a valid resource, then update the post.
- Scenario C: A newly deployed app route isn’t wired correctly. Path fix: verify route definitions and middleware; restart services and test across environments.
Appendix: Debugging Checklist
- Check the exact URL requested; confirm it matches existing routes.
- Review server, CMS, and application logs for 404 entries and their origin.
- Validate redirects for moved resources and ensure they return 301s when appropriate.
- Test across devices and browsers; clear caches to rule out stale responses.
- Update internal links and sitemaps; reindex updated URLs.
Steps
Estimated time: 45-60 minutes
- 1
Identify the exact URL
Copy the URL from the browser and verify there is a corresponding resource on the server or in the CMS. If the URL was auto-generated, check the route logic or slug settings.
Tip: Double-check casing and trailing slashes, which often trigger 404s. - 2
Check server and application logs
Review access and error logs for the 404 entry to see where the request originated and which resource was requested. This helps distinguish missing content from misrouted paths.
Tip: Filter logs to the specific URL and time window. - 3
Validate routing and redirects
Ensure routes map to existing resources. If a page moved, implement a 301 redirect to the new URL; if not, consider a friendly 404 page.
Tip: Avoid permanent 404s for pages that still exist. - 4
Fix content or create a redirect
Restore the resource or create a proper redirect chain to guide users and crawlers to relevant content.
Tip: Test the redirect with multiple user agents. - 5
Test across environments
Reproduce the issue in staging or local environments to confirm the root cause and ensure consistency after fixes.
Tip: Verify CDN and cache layers are bypassed during tests. - 6
Monitor and document
Set up monitoring for future 404s and document changes in a changelog or internal wiki.
Tip: Schedule regular audits of high-traffic URLs.
Diagnosis: User sees HTTP 404 Not Found when requesting a page
Possible Causes
- highBroken or moved URL
- mediumIncorrect routing or rewrite rules
- lowCaching or CDN serving stale content
Fixes
- easyRestore the resource or implement a 301 redirect to the correct URL
- easyFix routing or rewrite rules and clear caches
- mediumUpdate internal links and sitemap, then reindex
Frequently Asked Questions
What does HTTP 404 mean?
HTTP 404 means the server can’t locate the requested resource at the specified URL. It indicates a client-side issue with the path or resource. It does not imply a server-wide outage.
HTTP 404 means the page you asked for isn’t found at that URL.
Why is 404 different from 403 or 410?
A 404 indicates the resource isn’t found. A 403 means access is forbidden, and a 410 indicates the resource was intentionally removed and won’t return. Each status signals a different problem and requires different handling.
404 is not found; 403 is forbidden; 410 is gone for good.
Should I fix 404s for SEO?
Yes. Unhandled 404s can waste crawl budget and hurt user experience. Use friendly 404 pages and redirects where appropriate to preserve SEO value and guide users to relevant content.
Fix 404s or redirect when content isn’t available to protect SEO.
How do I fix a 404 in WordPress?
Check permalinks, update slugs, flush rewrite rules, and set redirects for moved posts or pages. A well-maintained sitemap and internal links help prevent new 404s.
WordPress users should check permalinks and use redirects for moved pages.
What’s the difference between a 404 and a 410?
A 404 means not found; a 410 means gone and not expected to return. 410 signals a permanent deletion, while 404 can be temporary or permanent non-existence.
404 is missing; 410 is permanently gone.
Top Takeaways
- Understand 404 means not found at the requested URL
- Prioritize redirects for moved pages to preserve SEO
- Regularly audit internal links to prevent 404s
- Use a helpful 404 page to guide users and maintain engagement
