Haproxy 1.8 ERR_HTTP2_FRAME_SIZE_ERROR when changing tune.bufsize with http2

Hello,

I’m facing an error with haproxy and http2.
our application use big cookies and so we need to change param tune.bufsize to more than 16k (actually tune.bufsize 32768).

With http1.1 it’s work perfectly but with http2 enabled we got a browser error “ERR_HTTP2_FRAME_SIZE_ERROR” (chrome)
if we rollback tune.bufsize to default everything work

haproxy socket show no error:
echo “show errors” | socat unix-connect:/var/lib/haproxy/stats stdio
Total events captured on [06/May/2020:15:44:36.053] : 0

it may be related to the frame size but i don’t know how to extend it:
https://http2.github.io/http2-spec/#FrameSize

Do you know how to deal with that?

Thanks for your help.

Regards,