I have the same problem, did you find the solution?
In my case, this started happening after I implemented the keyclock in my project. After activating the keyclock, the navigation was automatically redirected to HTTPS (port 8443) automatically and the error in Http2ServerConnection started to appear. the application works, however loading is slow, too many errors are issued, for each loaded javax.faces.resource the error is issued.
I believe my application is not in the right configuration to use SSL on Wildlfy. But neither is my requirement to use the SSL protocol. my application will run on a small intranet. So I disabled the safe navigation. Removing these lines from my WEB.XML: (had added when configuring the keycloak in the application.)
Now when I access my application through the url "http://localhost:8080/app" is ok, no error is triggered.