gRPC Received http2 header with status 307 Error C#

Question

I have 3 Projects: ClientA, ServerA, ServerB.

Client A is a client to the server ServerA, ServerA is both Server for ClientA and a client towards ServerB. They all share a .Net Framework Class Library, which contains the .proto file and the generated Clients / ServerImpls. The .proto file gets atomatically interpreted using:

ServerA can call methods from ServerB, but ClientA can not call methods from ServerA (see error in title).

The .proto file looks like this:

    message Ping{
         int64 timestamp = 1;
     }
     message Pong {
         int64 timestamp = 1;
     }

    service ServerAService {   
        rpc TestConnection(Ping) returns (Pong);
    }

    service ServerBService {   
        rpc TestConnection(Ping) returns (Pong);
    }

Client A is a .NET Framework 4.7.2 Excel Add-in with these packages:

It Connects to ServerA with this code:

    Channel channel = new Channel("127.0.0.1:" + 50051, ChannelCredentials.Insecure);
                client = new ServerAService.ServerAServiceClient(channel);
    if (client.TestConnection(new Ping { Timestamp = DateTime.Now.Ticks }, null) != null)
                { [...]

ServerA is a ASP.NET Core 3.1 Application with the ServerImpl started via Dependency Injection:

 app.UseEndpoints(endpoints =>
            {
                endpoints.MapGrpcService();
                endpoints.MapControllers();
                endpoints.MapBlazorHub();
                endpoints.MapFallbackToPage("/_Host");
            });

and, since IIS does not support gRPC, using Kestrel configured like this:

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup();
                    webBuilder.ConfigureKestrel(options =>
                    {
                        options.Listen(IPAddress.Any, 50051, listenOptions =>
                        {
                            listenOptions.Protocols = HttpProtocols.Http2;
                        });
                    });
                });

ServerA also has theese packages:

ServerA does the same as ClientA does to connect:

var channel = new Channel("localhost:50033", ChannelCredentials.Insecure);
                    ServerBClient serverb = new ServerBClient(channel);

                    if (serverb.TestConnection(new Ping(), null) != null)
                    { [...]

ServerB is also an ASP.NET Core 3.1 App:

app.UseEndpoints(endpoints =>
            {
                endpoints.MapGrpcService();
                endpoints.MapGet("/", async context =>
                {
                    await context.Response.WriteAsync("ServerB Running!");
                });
            });

With kestrel, too:

public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
            .ConfigureLogging(logging =>
            {
                logging.AddConsole();
            }
            ).ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup();
                    webBuilder.ConfigureKestrel(options =>
                    {
                        options.Listen(IPAddress.Any, 50033, listenOptions =>
                        {
                            listenOptions.Protocols = HttpProtocols.Http2;
                        });
                    });
                });

and theese packages:

When ClientA calls the ServerA.TestConnection procedure, the error "Received http2 header with status 307" occurs. ServerA can call the ServerB.TestConnection without a problem.

Before switching to ASP.NET Core 3.1 the ServerA and ServerB were running as .NET Framework Console Applications, and were just changed during a refactoring. When everything was running on .NET Framework, ClientA was able to ServerA.TestConnection successfully. Are grpc on .netframework and .netcore incompatible?

What does "Received http2 header with status 307" even mean? I hope someone has a clue.

Edit: As suggested by Marc i created a blank project to ultimately upload the test case to github, and could figure out from that that the implementation of "Blazor" is blocking gRPC here. So its not a .net FRAMEWORK <> Core compatiblity issue, its a Blazor <> gRPC issue. I will try to narrow down why blazor redirects the gRPC call, even though its on another port. Maybe gRPC and Blazor need to be run in different services after all.

gRPC Received http2 header with status 307 Error C#

0 Answers