203
Success
203 Non-Authoritative Information
The returned metadata is from a local or third-party copy, not from the origin server.
Definition (RFC 9110)
HTTP status code 203 203 Non-Authoritative Information is defined in RFC 9110 (HTTP Semantics), Section 15.3.4 — the current authoritative specification for HTTP semantics, published June 2022, which obsoletes the older RFC 7231 and RFC 2616.
Description
203 Non-Authoritative Information indicates that the request was successful, but the enclosed payload has been modified by a transforming proxy. The information may come from a cached copy, a CDN, or a middleware layer rather than directly from the origin server.
This is rarely used in modern web applications but may appear in proxy or gateway responses.
Common Causes
- CDN or proxy modifying headers or body
- Transformation middleware stripping sensitive fields
- Aggregation services combining data from multiple sources
How to Fix
- If you need authoritative data, bypass caches and connect directly to origin
- Document clearly which layers may transform responses
- Use
Varyheaders to communicate caching dimensions
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