Asp.net core 3.0 Grpc.AspNetCore.Server.ClientFactory Error

Grpc.Core.RpcException: Status(StatusCode=Internal, Detail="Error starting gRPC call: An error occurred while sending the request.")
   at Grpc.Net.Client.Internal.HttpClientCallInvoker.BlockingUnaryCall[TRequest,TResponse](Method`2 method, String host, CallOptions options, TRequest request)
   at Grpc.Core.Interceptors.InterceptingCallInvoker.<BlockingUnaryCall>b__3_0[TRequest,TResponse](TRequest req, ClientInterceptorContext`2 ctx)
   at Grpc.Core.ClientBase.ClientBaseConfiguration.ClientBaseConfigurationInterceptor.BlockingUnaryCall[TRequest,TResponse](TRequest request, ClientInterceptorContext`2 context, BlockingUnaryCallContinuation`2 continuation)
   at Grpc.Core.Interceptors.InterceptingCallInvoker.BlockingUnaryCall[TRequest,TResponse](Method`2 method, String host, CallOptions options, TRequest request)
   at GrpcService2.Chat.ChatClient.SendChat(ChatRequest request, CallOptions options) in C:\Users\Aries\Desktop\ConsoleApp3\ConsoleApp3\obj\Debug\netcoreapp3.0\ChatGrpc.cs:line 92
   at GrpcService2.Chat.ChatClient.SendChat(ChatRequest request, Metadata headers, Nullable`1 deadline, CancellationToken cancellationToken) in C:\Users\Aries\Desktop\ConsoleApp3\ConsoleApp3\obj\Debug\netcoreapp3.0\ChatGrpc.cs:line 88
   at WebApplication1.Controllers.TestController.GetName() in C:\Users\Aries\Desktop\ConsoleApp3\WebApplication1\Controllers\TestController.cs:line 25
   at lambda_method(Closure , Object , Object[] )
   at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

HEADERS

Cache-Control: no-cache Connection: keep-alive Content-Type: application/json Accept: / Accept-Encoding: gzip, deflate Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJuaWNrTmFtZSI6IuWPr-i-vum4rSIsImVtYWlsIjoiYWRtaW5AMTYzLmNvbSIsInVpZCI6IjB4MTAyNCIsImFwcENvZGUiOiIyMTQiLCJsb2dpblRpbWUiOiIyMDE5LTEwLTIyIDE2OjU1IiwiZXhwIjoxNTcxNzM4MTM2LCJpc3MiOiJodHRwOi8vMTI3LjAuMC4xIiwiYXVkIjoiemh1cXVlIn0.-W__S8RuM2bvj8t6ZaqwEZQ0nhjX0pc0vE_dXPyosAY Host: localhost:5000 User-Agent: PostmanRuntime/7.19.0 Content-Length: 249 Postman-Token: 605b5837-28b9-42e1-910c-a93a022f7a2a

Code:

   public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
            services.AddGrpcClient<Chat.ChatClient>(o =>
            {
                o.Address = new Uri("http://192.168.1.109:5001");
            });
        }


 public class TestController : ControllerBase
    {
        private readonly Chat.ChatClient _c;

        public TestController(Chat.ChatClient client)
        {
            _c = client;
        }

        [HttpGet]
        public ActionResult GetName()
        {
            var a = _c.SendChat(new ChatRequest { Name = "test request....." });
            return Ok(a);
        }
    }

[Justin-Lessard]

I’ve found a workaround for now.

Setting this flag inside the client seems to make it work.

AppContext.SetSwitch("System.Net.Http.SocketsHttpHandler.Http2UnencryptedSupport", true);

[Justin-Lessard]

Not the OP, but I’m able to reproduce. It’s working fine using https but when I try over http, I get the same error.

Exception thrown: ‘Grpc.Core.RpcException’ in System.Private.CoreLib.dll An unhandled exception of type ‘Grpc.Core.RpcException’ occurred in System.Private.CoreLib.dll Status(StatusCode=Internal, Detail=“Error starting gRPC call: An error occurred while sending the request.”)

There is nothing else in the debug logs. I’m able to access the RPC server without any issues using BloomRPC, so I suspect Grpc.Net.Client is at fault.

I’ve looked at the wireshark capture of a failed call using Grpc.Net.Client and here are the results.

No.	Time	Source	Destination	Protocol	Length	Info
1	0	192.168.0.161	172.17.131.244	TCP	66	5186  >  80 [SYN] Seq=0 Win=65535 Len=0 MSS=65495 WS=256 SACK_PERM=1
2	0.000497	172.17.131.244	192.168.0.161	TCP	66	80  >  5186 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1460 WS=256 SACK_PERM=1
3	0.00056	192.168.0.161	172.17.131.244	TCP	54	5186  >  80 [ACK] Seq=1 Ack=1 Win=2102272 Len=0
4	0.055721	192.168.0.161	172.17.131.244	TCP	339	5186  >  80 [PSH, ACK] Seq=1 Ack=1 Win=2102272 Len=285 [TCP segment of a reassembled PDU]
5	0.05687	192.168.0.161	172.17.131.244	TCP	59	[TCP segment of a reassembled PDU]
6	0.057291	172.17.131.244	192.168.0.161	TCP	54	80  >  5186 [ACK] Seq=1 Ack=291 Win=2102272 Len=0
7	0.058108	172.17.131.244	192.168.0.161	HTTP2	71	GOAWAY[0]
8	0.058161	192.168.0.161	172.17.131.244	TCP	54	5186  >  80 [ACK] Seq=291 Ack=18 Win=2102272 Len=0
9	0.058282	172.17.131.244	192.168.0.161	TCP	54	80  >  5186 [FIN, ACK] Seq=18 Ack=291 Win=2102272 Len=0
10	0.058314	192.168.0.161	172.17.131.244	TCP	54	5186  >  80 [ACK] Seq=291 Ack=19 Win=2102272 Len=0
11	0.074949	192.168.0.161	172.17.131.244	TCP	54	5186  >  80 [FIN, ACK] Seq=291 Ack=19 Win=2102272 Len=0
12	0.075183	172.17.131.244	192.168.0.161	TCP	54	80  >  5186 [ACK] Seq=19 Ack=292 Win=2102272 Len=0

It’s not really my area of expertise, but it looks like the client never initiate communication using HTTP2 and GRPC after the initial TCP handshake. The client just send the whole message over TCP and is rejected by the server.