HTTP 404 Not Found

What It Means

The HTTP 404 Not Found status code indicates that the server cannot find the requested resource. This is one of the most recognized status codes — the page simply doesn't exist at that URL.

Common Causes

Typo in URL: User or link has incorrect path
Deleted page: Resource was removed without redirect
Moved without redirect: URL changed but no 301 set up
Broken link: External site links to non-existent page
Case sensitivity: /Page vs /page on case-sensitive servers
Missing file extension: .html required but not provided
API route not defined: Endpoint doesn't exist

SEO Impact

404s themselves don't hurt SEO — they're a normal part of the web. However:

Broken internal links waste crawl budget
Lost backlinks lose link equity
Poor user experience increases bounce rate

Fix: Set up 301 redirects for moved/deleted pages with backlinks.

Example Response

HTTP/1.1 404 Not Found
Content-Type: application/json

{
  "error": "Not Found",
  "message": "The requested resource was not found",
  "path": "/api/users/999"
}

Custom 404 Pages

Nginx

server {
    error_page 404 /404.html;
    location = /404.html {
        root /var/www/html;
        internal;
    }
}

Next.js

// pages/404.js
export default function Custom404() {
  return <h1>404 - Page Not Found</h1>
}

Express.js

// 404 handler (must be last)
app.use((req, res) => {
  res.status(404).json({
    error: 'Not Found',
    path: req.path
  });
});

404 vs 410

Code	Meaning
404	"I don't know if this ever existed"
410	"This used to exist but was intentionally removed"

Good 404 Page Practices

Include search functionality
Link to popular pages or homepage
Keep the same site navigation
Make it clear it's a 404 (don't return 200)
Log 404s to find broken links

Frequently Asked Questions

What does HTTP 404 Not Found mean?

HTTP 404 Not Found indicates that the server cannot find the requested resource. This is one of the most recognized HTTP status codes. The URL may have been mistyped, the page may have been deleted, or the resource may have been moved without a redirect.

Do 404 errors hurt SEO?

404 errors themselves do not directly hurt SEO rankings. However, broken internal links waste crawl budget, lost backlinks forfeit link equity, and a poor user experience increases bounce rate. Set up 301 redirects for moved or deleted pages that have backlinks pointing to them.

What is the difference between 404 and 410?

404 means the server does not know if the resource ever existed. 410 Gone means the resource existed but was intentionally and permanently removed. Search engines de-index 410 pages faster than 404 pages, so use 410 when you deliberately remove content.

How should I handle 404 errors on my website?

Create a custom 404 page with your site navigation, search functionality, and links to popular pages. Log 404 errors to find broken links. Set up 301 redirects for URLs with backlinks. Never return a 200 status code for pages that don't exist (soft 404).

How do I monitor for 404 errors?

UptimeSignal monitors your endpoints and alerts you if they start returning 404 errors. This is especially useful for detecting broken deployments, accidental deletions, or routing configuration issues. Set up monitors for your critical URLs and API endpoints.