YARP behind YARP: Why HTTP/2 error code 'HTTP_1_1_REQUIRED' ?

[Sen-Gupta]

All proxies are running in docker container. (Lastest YARP)

We have a scenario, where we have a YARP instance (Let's call internet-proxy) facing internet running on https.

This instance forwards a few requests to another YARP instance (Let's call internal-proxy) running internally on http(no ssl here).
http://192.168.1.134:5823/
internal-proxy is running with Http2 as default protocol
"Kestrel": {
"EndpointDefaults": {
"Protocols": "Http2"
}
},

An http2 requests from client originates and hits (internet-proxy), since it is it a grpc call, we have configured it to be forwarded as http2 and require exact version.

Connection to internal-proxy fails with following:

external-proxy: (makes call to internal-proxy)
Proxying to http://192.168.1.134:5823/IEquitiesGrpcService/GetAllEntitiesAsync HTTP/2 RequestVersionExact no-streaming

But fails to perform Handshake with following error:

System.Net.Http.HttpRequestException: An error occurred while sending the request.
---> System.IO.IOException: The request was aborted.
---> System.IO.IOException: An HTTP/2 connection could not be established because the server did not complete the HTTP/2 handshake.
---> System.Net.Http.HttpProtocolException: The HTTP/2 server closed the connection. HTTP/2 error code 'HTTP_1_1_REQUIRED' (0xd).
at System.Net.Http.Http2Connection.ThrowProtocolError(Http2ProtocolErrorCode errorCode, String message)

Any suggestions?

[Tratcher]

no-streaming

This is suspect, that should say 'streaming' for gRPC calls. Can you collect full debug logs for the server?

[Sen-Gupta]

Never mind, it was not an issue with YARP.

It is cloudflare that forces Grpc calls to use GrpcWeb.