404 Not Found

The server could not find a resource at this URL. This says nothing about whether the resource will exist later — only that it does not exist now.

What It Means

404 Not Found is a client error (4xx class), meaning the problem is with the request URL, not the server. The server is reachable and working; it simply has no resource at the path the client requested. A 404 does not indicate whether the resource ever existed or whether it might exist in the future.

If you know the resource is gone permanently and will never return, prefer 410 Gone. 410 signals to search engines and link cleaners that they should remove the URL from their indexes immediately, whereas 404 leaves the permanence ambiguous.

Common Causes

• Typo in the URL. A character wrong in the path, a missing segment, or a case mismatch on a case-sensitive server.
• Content moved or deleted. The resource existed at this URL but was removed or relocated without setting up a redirect.
• Broken inbound link. Another page or external site links to a URL that no longer exists.
• URL structure change. A CMS migration or routing change altered the URL format, invalidating old URLs.
• Trailing slash mismatch. The server treats /page and /page/ as different paths; one may 404 while the other serves content.

How to Diagnose

Use the Probe tool to confirm the exact status code returned. Check whether the URL was recently changed by looking at redirect history. If the resource was moved, add a 301 redirect from the old URL to the new one to preserve inbound links and search engine rankings.

Watch for soft 404s: pages that display "not found" or "no results" messaging but return a 200 status code. Search engines index these as valid pages, which dilutes crawl budget and can suppress rankings. Your server should return 404 (or 410) for any URL that has no real content.