HTTP 404 Not Found — Meaning, Causes & How to Fix
The server cannot find the requested resource; the URL is not recognized.
- Code
- 404
- Name
- Not Found
- Class
- 4xx Client Error
- Specification
- RFC 9110 §15.5.5
- Cacheable by default
- Yes — heuristically cacheable by default
What HTTP 404 means
404 Not Found means the server has nothing at this URL. It does not say whether the absence is temporary or permanent (that is what 410 Gone is for). It is the most common error on the web and is completely normal for URLs that never existed.
Common causes
- A typo in the URL or a broken internal/external link.
- A page was deleted or its slug changed without a redirect.
- A rewrite rule or routing configuration is wrong.
- Case-sensitive file names on Linux servers (
/Aboutvs/about).
How to fix it
For site owners
- If the content moved, add a 301 redirect to the new URL.
- Fix internal links pointing to the missing page.
- Serve a helpful custom 404 page (search, popular links) — but keep the 404 status.
- Check Search Console’s Page indexing report for “Not found (404)” URLs that deserve redirects.
For visitors & developers
- Check the URL for typos and try the site’s search.
- Look for the page in the Wayback Machine if it was removed.
SEO impact
404s do not harm the rest of your site. Google drops 404 URLs from the index after recrawling them. What hurts is losing valuable pages and their backlinks: redirect removed pages with 301 to a relevant replacement, and never return 200 for missing pages (soft 404).
Example 404 response
HTTP/1.1 404 Not Found
Content-Type: text/html; charset=utf-8
Cache-Control: max-age=300
Content-Length: 2048Related status codes
Check or look up another code
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Open HTTP Status Codes tool →All status codesFrequently asked questions
What does HTTP 404 mean?
HTTP 404 Not Found is a 4xx Client Error status code. The server cannot find the requested resource; the URL is not recognized.
Do 404 errors hurt SEO?
Not for the site as a whole. Google expects 404s for URLs that do not exist. Only fix the ones that were real pages or have backlinks, by redirecting them to a relevant page.
404 or 410 for a deleted page?
Both remove the page from the index. 410 says explicitly it is gone for good; in practice Google treats them very similarly.
Which specification defines 404?
It is defined in RFC 9110 §15.5.5.
Is a 404 response cacheable?
Yes. 404 is one of the codes RFC 9110 §15.1 lets caches store heuristically, so it can be reused without explicit caching headers. Send Cache-Control to control how long.