But, if you see RFC2616 for proxy, there is no reference about to consider proxy server as next hop. RFC 2616 says that proxy forwards request according to next hop (if next hop is or it's not compliant to HTTP/1.1). I think proxy, even if it compliants with HTTP/1.0, should have only to examine the next hop without taking care of itself (that is like http protocol 1.1 -1.0) You correct me if I wrong... Requirements for HTTP/1.1 proxies: 1- If a proxy receives a request that includes an Expect request- header field with the "100-continue" expectation, and the proxy either knows that the next-hop server complies with HTTP/1.1 or higher, or does not know the HTTP version of the next-hop server, it MUST forward the request, including the Expect header field. 2- If the proxy knows that the version of the next-hop server is HTTP/1.0 or lower, it MUST NOT forward the request, and it MUST respond with a 417 (Expectation Failed) status. 3- Proxies SHOULD maintain a cache recording the HTTP version numbers received from recently-referenced next-hop servers. 4- A proxy MUST NOT forward a 100 (Continue) response if the request message was received from an HTTP/1.0 (or earlier) client and did not include an Expect request-header field with the "100-continue" expectation. This requirement overrides the general rule for forwarding of 1xx responses (see section 10.1) -----Messaggio originale----- Da: Henrik Nordström [mailto:henrik@xxxxxxxxxxxxxxxxxxx] Inviato: Monday, February 22, 2010 12:37 AM A: Riccardo Castellani Cc: Amos Jeffries; squid-users@xxxxxxxxxxxxxxx Oggetto: Re: HTTP/1.0 417 Expectation failed sön 2010-02-21 klockan 22:55 +0100 skrev Riccardo Castellani: > according RFC what's the case for Squid 2.7 about "HTTP/1.0 417 Expectation > failed", "X-Squid-Error: ERR_INVALID_REQ 0" > > A, B, C ,D ? B, as Squid-2.7 has an internal HTTP/1.0 hop. Regards Henrik