# What is 404 error?

> A 404 error is the ‘page not found’ message a website shows when someone visits an address that does not exist, often because a page was deleted or renamed.

- Source: https://nerdsharks.com/glossary/404-error
- Publisher: Nerdsharks (Exeter, Devon, UK)
- Updated: 2026-09-26

Also called: page not found, broken link, dead link, HTTP 404.

Every time a browser asks for a page, the server replies with a number called a status code. 404 means ‘not found’: the address does not lead to anything.

404s happen when a page has been deleted, its address changed, or someone mistyped a link. The odd one is normal and harmless. Lots of them, especially on pages people used to visit, is a problem.

A good 404 page apologises briefly and points people to your main services and contact details, rather than a blank error.

## Why it matters for a small business

When you rebuild a website and page addresses change, old links from Google, directories and people's bookmarks can all lead to 404s. Visitors hit a dead end and leave, and pages that used to rank can lose their place. Redirects fix this.

**Example:** A roofer's old site had a page at /services/flat-roofs. The new site uses /flat-roofing. Without a redirect, anyone clicking the old Google result lands on ‘Page not found’.