Can we use http2 in Haproxy as frontend protocol and use http 1.1 protocol in backend server

I have 1 haproxy 1.6.4 server which load balances to two backend apache 2.2.3 servers. What I want to do is use http2 in haproxy as frontend which browsers can talk to and use http1.1 to backend apache servers (conversion from http 2 to http 1.1). Is this architecture possible, or if http2 is used by browser then backend apache should support http2 too ?. Please advise on this issue.

No, Haproxy does not support HTTP/2 yet.

So version 1.6.4 does not support http2 or haproxy does not support http2 at all.

haproxy does not support http2 at all, for now.