203 Non-Authoritative Information

This response code indicates that the request sent was success, but was modified. The request was modified by a 3rd party. Usually a transforming proxy that makes changes between the origin and the receiving server.

While 203 is like the other warning code 214 [Transformation Applied], this [203] code usually happens when changes are made to the header.

Most users will see this if a proxy, or some other 3rd party, has modified header data from the original website, or server.

The HTTP 203 Non-Authoritative Information response status indicates that the request was successful but the enclosed payload has been modified by a transforming proxy from that of the origin server’s 200 (OK) response .

The 203 response is similar to the value 214, meaning Transformation Applied, of the Warning header code, which has the additional advantage of being applicable to responses with any status code.