Grpc-dotnet: gRPC call throws an exception: Status(StatusCode=Internal, Detail="Bad gRPC response. Response protocol downgraded to HTTP/1.1.")

[yshteinm]

I checked all "Closed" issues I could find. None of them helped.

What version of gRPC and what language are you using?

Using C# with
Nuget packages:
Grpc.Net.Client - 2.28.0
Grpc.Tools - 2.28.1
Google.Protobuf v3.11.4

What operating system (Linux, Windows,...) and version?

Windows 10 Pro

What runtime / compiler are you using (e.g. .NET Core SDK version dotnet --info)

Microsoft Visual Studio Community 2019 Version 16.5.3
Building .Net Core 3.1 Console app

.NET Core SDK (reflecting any global.json):
Version: 3.1.201
Commit: b1768b4ae7

Runtime Environment:
OS Name: Windows
OS Version: 10.0.18363
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.1.201\

Host (useful for support):
Version: 3.1.3
Commit: 4a9f85e9f8

.NET Core SDKs installed:
3.1.201 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

What did you do?

Used different options to create a channel. It would be too much if I showed all options I tried with
different SocketsHttpHandler and HttpClient and GrpcChannelOptions and HttpClientHandler. The basic code which should work is below.

static string username = "un";
static string password = "pp";
static byte[] data = Encoding.ASCII.GetBytes(username + ":" + password);
static string encodedCredentials = System.Convert.ToBase64String(data);

private static GrpcChannel CreateAuthenticatedChannel(string address)
        {
            //using CallCredentials and below SslCredentials
            var credentials = CallCredentials.FromInterceptor((context, metadata) =>
            {
                metadata.Add("Authorization", $"Basic {encodedCredentials}");
                metadata.Add("Content-Type", "UTF8");
                //metadata.Add("ContentType", "UTF8");
                //metadata.Add("User-Agent", "grpc-dotnet/2.25.0.0");
                //metadata.Add("grpc-accept-encoding", "identity,gzip");
                //metadata.Add("Content-Type", "application/grpc");
                return Task.CompletedTask;
            });
            // SslCredentials is used here because this channel is using TLS.
            var channel = GrpcChannel.ForAddress(address, new GrpcChannelOptions
            {
                Credentials = ChannelCredentials.Create(new SslCredentials(), credentials)
            });
            return channel;
        }

Then call the service

var channel = CreateAuthenticatedChannel("https://mysite");
var client = new MyDbService.MyDbServiceClient(channel);
var result = client.usersearch(new UserSearch());

What did you expect to see?

Expect not to get an exception with
Status(StatusCode=Internal, Detail="Bad gRPC response. Response protocol downgraded to HTTP/1.1.")

What did you see instead?

An exception

[JamesNK]

The protocol is being downgraded to HTTP/1.1. What server are you using? Does the port support HTTP/2?

[yshteinm]

It is third-party system. They said they support protobuf which I think implies that they do support HTTP/2

[JamesNK]

Either the server or a proxy inbetween the client and the server is downgrading the connection to HTTP/1.1. That is out of Grpc.Net.Client's control.

[anurse]

Closing as there's no actionable work for us here. Some intermediate (or the server itself) is downgrading to HTTP/1.1 and gRPC requires HTTP/2.

[yshteinm]

Cannot accept that. I confirmed that server does support HTTP/2 and I am not sure what you mean by "intermediate" server. I cannot guarantee that every server on the way supports HTTP/2 which they should as they work as proxies. Unfortunately will not be able to use gRPC till it matures.