404 Not Found
4xx Client error
Nothing lives at that address — the URL is wrong or the page is gone.
| On the wire | HTTP/1.1 404 Not Found |
|---|---|
| Code | 404 |
| Is it an error | Yes — this is an error |
| Category | 4xx Client error |
The problem is on the request side; sending the same thing again will fail again.
How to read this
- The first digit of a status code carries the meaning: 4 means the request, 5 means the server.
- 404 means "not there"; 403 means "there, but not for you". Swapping them makes debugging slower.
- Header names are case-insensitive — Content-Type and content-type are the same header.
- Caching and CORS problems usually come down to one header line, visible in the browser’s network tab.
Frequently asked questions
Q. What does HTTP 404 Not Found mean?
Nothing lives at that address — the URL is wrong or the page is gone.
Q. What does 404 Not Found look like on the wire?
It travels as HTTP/1.1 404 Not Found
Q. Is 404 Not Found an error?
Yes. A code starting with 4 blames the request; one starting with 5 blames the server.
Q. What group does 404 Not Found belong to?
The 4xx client error group; the rest of that group is listed further down.