304 Not Modified
3xx Redirection
What you have is still current — reuse it. No body is sent, which is what makes caching fast.
| On the wire | HTTP/1.1 304 Not Modified |
|---|---|
| Code | 304 |
| Is it an error | No — not an error |
| Category | 3xx Redirection |
Go somewhere else — the distinction is permanent versus temporary.
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 304 Not Modified mean?
What you have is still current — reuse it. No body is sent, which is what makes caching fast.
Q. What does 304 Not Modified look like on the wire?
It travels as HTTP/1.1 304 Not Modified
Q. Is 304 Not Modified an error?
No — it is part of a normal exchange, not a failure.
Q. What group does 304 Not Modified belong to?
The 3xx redirection group; the rest of that group is listed further down.