5. Operational Issues

This section preserves the RFC text for optimistic HTTP/1.1 protocol transitions, including request smuggling risks, parser exploit risks, existing Upgrade tokens, HTTP CONNECT requirements, and IANA status.

5.  Operational Issues

   If the server rejects the transition request, the connection can
   continue to be used for HTTP/1.1.  There is no general requirement to
   close the connection in response to a rejected transition, and
   keeping the connection open has performance advantages if additional
   HTTP requests to this server are likely.  Thus, it is normally
   inappropriate to close the connection in response to a rejected
   transition.