404 is one of the common HTTP status codes, indicating that the server cannot find the requested resource. Visitors usually see a "Page Not Found" message.
It should be noted that 404 itself is not a fault, but a normal response. Incorrect addresses, removed content, and expired links can all produce 404s. What really deserves attention is the number and source: occasional 404s need no handling, while a large number of long-standing dead links will affect the experience and indexing.
Why It Happens
- A visitor manually enters an incorrect address
- Content has been deleted or renamed without a redirect being set up
- A link within a page on the site points to an address that is no longer valid
- A link referenced by an external website becomes invalid after a redesign
How to Handle It at the Page Level
When a replacement page does exist, the correct approach is to set up a redirect to the new address so that visitors and search engines can reach it smoothly.
For content that is genuinely no longer available, you can configure a custom error page with clear explanations. A good error page should include: a clear message, a site search entry point, links to main sections, and necessary contact information. Its purpose is not to apologize, but to guide visitors back to a valid path.
How to Govern It at the Site Level
Governance aims to address "why dead links continue to be generated." Several feasible approaches:
- Regularly scan internal links with a link-checking tool and fix invalid ones promptly
- Check 404 records in server logs to understand which non-existent addresses visitors are actually accessing
- When adjusting content or taking pages offline, set up redirects and update internal references at the same time
- Keep the navigation structure clear to reduce link confusion caused by deeply nested pages
- Use the site's sitemap and crawling rules to prevent search engines from repeatedly accessing invalid addresses
404s cannot be completely eliminated, nor should all invalid addresses be redirected to the homepage just to eliminate them—that would both mislead visitors and prevent search engines from understanding the site's true structure.