HTTP error codes explained: 403, 404, 500, 502, 503 and 504
Updated 31 October 2026
Every time your browser asks a website for a page, the server answers with a three-digit status code. You usually never see it, but when something goes wrong it can tell you a lot about where the problem is. The first digit gives the general meaning:
- 2xx — success. The page was sent.
- 3xx — redirect. The page lives somewhere else, and your browser is sent there.
- 4xx — a problem with the request: the page doesn’t exist, or you’re not allowed to see it. The website itself is usually working.
- 5xx — a problem on the website’s side. These are the codes that usually mean a site is down.
The common codes
| Code | Name | What it means | Is the site down? |
|---|---|---|---|
| 200 | OK | Everything worked. | No |
| 301 / 302 | Moved | The page has moved (permanently or temporarily) and you’re being redirected, for example from bbc.co.uk to www.bbc.co.uk. | No |
| 403 | Forbidden | The server is refusing the request. Often caused by bot protection, a country block or a permissions setting. | Usually not |
| 404 | Not Found | That page doesn’t exist, but the website is answering. | No |
| 429 | Too Many Requests | You (or your network) have sent too many requests too quickly and are being slowed down. | No |
| 500 | Internal Server Error | Something broke inside the website’s own software. | Yes, at least partly |
| 502 | Bad Gateway | A server in the middle got a bad answer from the server behind it. | Yes, usually |
| 503 | Service Unavailable | The site is overloaded or down for maintenance. | Yes, usually temporary |
| 504 | Gateway Timeout | A server in the middle waited too long for the server behind it to reply. | Yes, usually |
Cloudflare’s 52x errors
Many websites sit behind Cloudflare. When Cloudflare can’t get a proper answer from the website’s own server, it shows its own error page with a code in the 520s — for example 521 (the web server is down), 522 (the connection timed out) or 525/526 (a problem with the site’s security certificate). All of these mean the problem is on the website’s side, not yours.
Can I fix it?
For 4xx codes, sometimes: check the address for a 404, sign in or switch off a VPN for a 403, and wait a few minutes for a 429. For 5xx codes, almost never — the website’s owners have to fix them, and waiting is the only option. You can run a check every few minutes to see when it comes back.
Why does Website Down Now count 403 as “Up”?
A 403 means the server is online and answering — it just doesn’t want to talk to automated checkers like ours. Many large websites do this to block bots, while still loading normally for real people in a browser. Counting it as “Down” would give false alarms.
Find out in seconds whether a site is down for everyone or just you.
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