3xx Redirection

304 Not Modified

The cached copy is still valid; nothing new to download.

What 304 means

The answer to a conditional request (If-None-Match or If-Modified-Since): the resource hasn't changed since the client's cached version, so the server sends no body. It saves bandwidth.

Common causes

The client sent an ETag or date it already has and the resource is unchanged.

How to fix it

If you're calling an API

Use your cached copy. If you see 304 without a cache, stop sending If-None-Match / If-Modified-Since.

If you run the server

Send ETag or Last-Modified headers so clients can make conditional requests.

Should you retry?

No need: use the cached version.

Example response

HTTP

HTTP/1.1 304 Not Modified
ETag: "33a64df5"

Related headers: ETag, If-None-Match, Last-Modified, If-Modified-Since.

Defined in: RFC 9110 (HTTP Semantics). 304 is a redirection.

HTTP 304 FAQ

What does HTTP 304 mean?

304 Not Modified: The cached copy is still valid; nothing new to download. The answer to a conditional request (If-None-Match or If-Modified-Since): the resource hasn't changed since the client's cached version, so the server sends no body. It saves bandwidth.

Is 304 a client or server error?

Neither: 304 is a redirection response (3xx). Further action (usually following a new URL) is needed.

How do I fix a 304 error?

Use your cached copy. If you see 304 without a cache, stop sending If-None-Match / If-Modified-Since.

Should I retry after a 304?

No need: use the cached version.

Other 3xx status codes

All HTTP status codes