I too am seeing this issue with with haproxy 1.8.26-1ppa1~bionic on Ubuntu 18.04.4 LTS.
On Chrome (84.0.4147.105), this results in the 'net::ERR_HTTP2_PROTOCOL_ERROR 200' console error, either on the primary page load or on load of other page resources. In Firefox (79.0), no console errors are reported but loading of some resources must be impacted, as either the page render is off due to CSS issues, or page JS interactions don't work as expected. I was tempted to try rolling back to 1.8.25, however in testing I noticed that haproxy log records a 'CD' status: Aug 5 19:25:17 XX haproxy[1219]: 167.179.162.204:15163 [05/Aug/2020:19:25:17.077] http-https-vip~ XX-pool/XX-01 0/0/0/6/6 200 16754 - - CD-- 1/1/0/0/0 0/0 "GET /sites/default/files/js/js_b5CVpcMqsurBS2z_ljLBm79RgnowXJ_h8ce_XBlFrNg.js HTTP/1.1" I believe this is due to the client prematurely closing the connection. As a hunch, I disabled http/2 protocol, and the situation was resolved in both Chrome and Firefox. I have seen no mention of this issue on the Issue Tracker and was about to create a new Issue, when the template told me to check the mailing list first. Any instructions on how to capture additional information to assist with the issue would be appreciated. At this stage this is affecting live traffic and so I am going to either disable http/2 or upgrade to 2.x. Cheers, Oliver Kelly
