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
- Usually nothing — the content is there, just altered by a proxy along the way
- 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
- Serve over HTTPS — a proxy cannot transform what it cannot read
- 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 The request worked and the response contains what was asked for.
- 204 No Content The request succeeded and there is deliberately no body to send back.
- 201 Created The request succeeded and a new resource was created as a result.
- 206 Partial Content The server is returning only the requested byte range of a file, not the whole t
- 202 Accepted The request was accepted for processing, but the work has not finished yet.
- 207 Multi-Status A WebDAV response carrying separate status codes for several resources at once.
- 205 Reset Content The request succeeded and the client should clear the form that sent it.
- 208 Already Reported Inside a WebDAV multi-status response, this member was already listed earlier so
- 226 IM Used The server is returning a delta against a copy the client already has, rather th