203 Status Code Explained
A 203 status code means that the request was received and understood, and that information sent back about the response is from a third party, rather than the original server. This is virtually identical in meaning to a 200 status code.
Why it Occurs
The returned metainformation in the entity-header is not the definitive set as available from the origin server, but is gathered from a local or a third-party copy. The set presented MAY be a subset or superset of the original version. For example, including local annotation information about the resource might result in a superset of the metainformation known by the origin server.
What it Means
This code may be used in place of 200 when the sender has a reason to believe that the information in the response's entity headers is different from what the origin server would send.