Error 453--End Reached
From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:
10.4.25 453 End Reached
You have reached the end of the Internet. There are no further links. No indication is given of whether the condition is temporary or permanent.
If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.