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HTTP Status Code
203 Non-Authoritative Information
SuccessThe request succeeded, but the response was modified by a proxy or intermediate server.
HTTP status code reference, response example, common causes, fixes, and related status codes.
What does HTTP 203 Non-Authoritative Information mean?
HTTP 203 Non-Authoritative Information is a status code sent by a server to indicate the result of an HTTP request.
Status codes help browsers, APIs, apps, and backend systems understand whether a request succeeded, failed, was redirected, or needs additional action.
In practice, HTTP 203 Non-Authoritative Information usually appears when a server responds under specific request, validation, permission, or infrastructure conditions.
Response example
HTTP/1.1 203 Non-Authoritative Information Content-Type: application/json
HTTP example
HTTP/1.1 203 Non-Authoritative Information
Common causes
- A proxy or CDN modified the original server response
- Transformation proxies adding or removing metadata
- Third-party intermediaries altering response content
How to fix it
- No fix required if the modification is expected
- Bypass the proxy if the original unmodified response is needed
Common mistakes
- Assuming the status code alone explains the full backend issue
- Ignoring related response headers that add important context
- Treating temporary errors as permanent failures
- Retrying too aggressively without checking the cause
- Debugging the frontend only when the problem is server-side
How browsers and APIs use it
Browsers, APIs, and backend services use HTTP status codes to understand the outcome of a request. Depending on the status code, an application may render content, retry a request, redirect the user, show an error, or trigger a different flow in the client or server.
Practical developer insight
203 is rarely used in practice. It signals that the response body is a transformed version of the original, not the raw origin response. In practice, most CDNs and proxies modify responses without ever returning 203.