304 Not Modified
The cached copy is still valid, so no body is sent.
| Class | Redirection (3xx) |
|---|---|
| Defined in | RFC9110, Section 15.4.5 |
| Cacheable by default | No, unless explicit freshness headers allow it |
Common causes
- The client sent If-None-Match or If-Modified-Since and the resource has not changed.
- A browser is revalidating a cached file.
What to do
Make sure your server sends validators (ETag or Last-Modified) so clients can revalidate and you save bandwidth. A 304 never has a body.
Related codes
- 200 OK: The request succeeded. What the body contains depends on the method used.
- 206 Partial Content: The server is delivering only part of the resource, as requested with a Range header.
- 412 Precondition Failed: A precondition in the request headers, such as If-Match, evaluated to false.