---
title: "203 Non-Authoritative Information — what it means and how to fix it"
description: "The request succeeded, but an intermediary modified the response on the way. What causes an HTTP 203, what to try as a visitor, and what to check if it is your own site."
url: https://atoneplace.net/error/203/
site: "At One Place"
---

# HTTP 203 — Non-Authoritative Information

**HTTP 203: Non-Authoritative Information**

The request succeeded, but an intermediary modified the response on the way.

## What 203 actually means

The response would have been a 200, except that something between the origin and the client changed it — a transforming proxy that recompressed images, stripped headers, or injected content. The 203 exists so a client can tell that what it received is not byte-for-byte what the origin sent. It is rare in the wild, mostly because transforming proxies usually do not bother to say so.

## Common causes

- A transforming proxy compressed or rewrote the payload
- A corporate filter or carrier proxy modified the response
- A caching layer served a transformed copy

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

1. Usually nothing — the content is there, just altered by a proxy along the way
2. If images look degraded on mobile data, your carrier may be compressing them; a VPN or HTTPS-only browsing typically stops it

## If it's your site

1. Serve over HTTPS — a proxy cannot transform what it cannot read
2. Send `Cache-Control: no-transform` if the exact bytes matter

## Reference

- **Status code:** 203
- **Reason phrase:** Non-Authoritative Information
- **Category:** 2xx — Success
- **Cacheable by default:** Yes
- **Defined in:** RFC 9110 §15.3.4

## Common questions

### What does HTTP 203 mean?

The request succeeded, but an intermediary modified the response on the way. The response would have been a 200, except that something between the origin and the client changed it — a transforming proxy that recompressed images, stripped headers, or injected content. The 203 exists so a client can tell that what it received is not byte-for-byte what the origin sent.

### How do I fix a 203 error?

Usually nothing — the content is there, just altered by a proxy along the way

### Is 203 a client error or a server error?

203 is in the 2xx range, which means success. It is not an error at all.

## Related pages

- [200 OK](https://atoneplace.net/error/200/)
- [204 No Content](https://atoneplace.net/error/204/)
- [201 Created](https://atoneplace.net/error/201/)
- [206 Partial Content](https://atoneplace.net/error/206/)
- [202 Accepted](https://atoneplace.net/error/202/)
- [207 Multi-Status](https://atoneplace.net/error/207/)
- [205 Reset Content](https://atoneplace.net/error/205/)
- [208 Already Reported](https://atoneplace.net/error/208/)
- [226 IM Used](https://atoneplace.net/error/226/)

## 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)