---
title: "304 Not Modified — what it means and how to fix it"
description: "Your cached copy is still current, so the server is not sending the file again. What causes an HTTP 304, what to try as a visitor, and what to check if it is your own site."
url: https://atoneplace.net/error/304/
site: "At One Place"
---

# HTTP 304 — Not Modified

**HTTP 304: Not Modified**

Your cached copy is still current, so the server is not sending the file again.

## What 304 actually means

The client asked "has this changed since the version I already have?" using `If-None-Match` or `If-Modified-Since`, and the server checked and said no. The response has no body at all, which is the whole point: a 304 costs a few hundred bytes instead of re-downloading an image. A page full of 304s in the network panel is a well-cached page, not a broken one.

## Common causes

- The client sent an `If-None-Match` header whose ETag matched the current one
- The client sent `If-Modified-Since` and the resource has not changed
- A CDN revalidated a stale cache entry against the origin

## If you're just trying to view the page

1. Nothing — this is caching working as designed and makes pages load faster
2. If you are seeing an outdated version of a page, force a reload with Ctrl+F5 (Windows) or ⌘ + Shift + R (Mac) to bypass the cache

## If it's your site

1. A 304 must not include a body; some frameworks accidentally send one and break clients
2. If updated assets are not reaching users, check whether your ETag is stable across servers — load-balanced fleets that generate ETags from inode numbers produce inconsistent results
3. Content-hashed filenames plus long `Cache-Control: immutable` avoid the revalidation round trip entirely

## Reference

- **Status code:** 304
- **Reason phrase:** Not Modified
- **Category:** 3xx — Redirection
- **Defined in:** RFC 9110 §15.4.5

## Common questions

### What does HTTP 304 mean?

Your cached copy is still current, so the server is not sending the file again. The client asked "has this changed since the version I already have?" using `If-None-Match` or `If-Modified-Since`, and the server checked and said no. The response has no body at all, which is the whole point: a 304 costs a few hundred bytes instead of re-downloading an image.

### How do I fix a 304 error?

Nothing — this is caching working as designed and makes pages load faster

### Is 304 a client error or a server error?

304 is in the 3xx range, which means redirection. It is not an error at all.

## Related pages

- [301 Moved Permanently](https://atoneplace.net/error/301/)
- [302 Found](https://atoneplace.net/error/302/)
- [307 Temporary Redirect](https://atoneplace.net/error/307/)
- [308 Permanent Redirect](https://atoneplace.net/error/308/)
- [303 See Other](https://atoneplace.net/error/303/)
- [300 Multiple Choices](https://atoneplace.net/error/300/)
- [305 Use Proxy](https://atoneplace.net/error/305/)
- [306 (Unused)](https://atoneplace.net/error/306/)

## Sources

- Hypertext Transfer Protocol (HTTP) Status Code Registry — IANA (https://www.iana.org/assignments/http-status-codes/)
- RFC 9110: HTTP Semantics — IETF (https://www.rfc-editor.org/rfc/rfc9110.html)