The Danish developer is calling for the HTTP Working Group to abandon their current work on "HTTP/2", admit defeat, and start over. This comes after the working group acknowledged "we may not get everything right in [HTTP 2.0]" with some discussions about HTTP 3.0 already underway even though the 2.0 specification hasn't been finalized.
HTTP 2.0 is based upon Google's SPDY protocol for improving the performance of the protocol. Poul-Henning argues that SPDY is still far from perfect and "there are numerous hard problems that SPDY doesn't even get close to solving, and that we will need to make some simplifications in the evolved HTTP concept if we ever want to solve them."
Poul-Henning argues that SPDY is a "very good and worthwhile prototype" but suggests "Wouldn't we get a better result from taking a much deeper look at the current cryptographic and privacy situation, rather than publish a protocol with a cryptographic band-aid which doesn't solve the problems and gets in the way in many applications?"
His entire mailing list post can be read in full via the HTTP WG mailing list.