Unable to resolve service for type 'Microsoft.AspNetCore.SignalR.Hub`1[Ixxxx]' while attempting to activate 'xxxxx'

[ViacheslavUKR]

I define my typed SignalR Hub service as

            services.AddSignalR()
                    .AddHubOptions<OutputMessages>(options =>
                    {
                        options.EnableDetailedErrors = true;
                    });
           app.UseEndpoints(endpoints =>
                   {
                       endpoints.MapHub<OutputMessages>("/OutputMessages", options =>
                       {
                             options.Transports =
                             HttpTransportType.WebSockets |
                             HttpTransportType.LongPolling;
                       });
                   });

Then define interface IOutputMessage and realization:

    public class OutputMessages : Hub<IOutputMessages>
    {
        public OutputMessages(Hub<IOutputMessages> hubContext, ILogger<OutputMessages> logger, ApplicationDbContext dbContext)
        {

Than inject this service to comtroller

    public class ApplicationAPIController : ControllerBase
    {
        public ApplicationAPIController(ILogger<ApplicationAPIController> logger, ApplicationDbContext dbContext, IConfiguration Configuration, CoreObjectDumper.CoreObjectDumper dump, IHubContext<OutputMessages, IOutputMessages> _outputMessages)
...
              outputMessages.Clients.All.AdminMessages2(sessionData.Result.UserId, "Used Stop", false);

After I try to connect to my SignalR hub I receive

info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint '/OutputMessages'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished in 87.8426ms 101
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 POST http://localhost:5000/OutputMessages/negotiate?negotiateVersion=1  0
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint '/OutputMessages/negotiate'
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionManager[1]
      New connection tphQJH1K2qR9XAtDyRbH5w created.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher[10]
      Sending negotiation response.
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint '/OutputMessages/negotiate'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished in 19.5426ms 200 application/json
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 GET http://localhost:5000/OutputMessages?id=JQSyzJUvPHGEcquo1UwfrA
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint '/OutputMessages'
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher[4]
      Establishing new connection.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[1]
      Socket opened using Sub-Protocol: '(null)'.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[5]
      OnConnectedAsync started.
dbug: Microsoft.AspNetCore.SignalR.Internal.DefaultHubProtocolResolver[2]
      Found protocol implementation for requested protocol: json.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionContext[1]
      Completed connection handshake. Using HubProtocol 'json'.
fail: Microsoft.AspNetCore.SignalR.HubConnectionHandler[1]
      Error when dispatching 'OnConnectedAsync' on hub.
System.InvalidOperationException: Unable to resolve service for type 'Microsoft.AspNetCore.SignalR.Hub`1[SignalR.IOutputMessages]' while attempting to activate 'SignalR.OutputMessages'.
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
   at lambda_method(Closure , IServiceProvider , Object[] )
   at Microsoft.AspNetCore.SignalR.Internal.DefaultHubActivator`1.Create()
   at Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher`1.OnConnectedAsync(HubConnectionContext connection)
   at Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher`1.OnConnectedAsync(HubConnectionContext connection)
   at Microsoft.AspNetCore.SignalR.HubConnectionHandler`1.RunHubAsync(HubConnectionContext connection)
dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[6]
      OnConnectedAsync ending.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[4]
      Waiting for the application to finish sending data.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[2]
      Socket closed.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionManager[2]
      Removing connection JQSyzJUvPHGEcquo1UwfrA from the list of connections.

What I doing wrong?

[BrennanConroy]

Why is Hub<IOutputMessages> hubContext in the constructor of your Hub? That's what is causing issues.

[ViacheslavUKR]

Directly it's impossible. Maybe need something more...

[BrennanConroy]

Why did you change your hub definition back to the wrong version?

Use IHubContext<OutputMessages, IOutputMessages> in the constructor and keep the hub defined as public class OutputMessages : Hub<IOutputMessages>

[ViacheslavUKR]

it's impossible, sorry. If I type this line

public OutputMessages(IHubContext<OutputMessages, IOutputMessages> hubContext, ILogger<OutputMessages> logger, ApplicationDbContext dbContext)

I have received compilation error

Error CS0311 The type 'OutputMessages' cannot be used as type parameter 'THub' in the generic type or method 'IHubContext<THub, T>'. There is no implicit reference conversion from 'OutputMessages' to 'Microsoft.AspNetCore.SignalR.Hub<IOutputMessages>'.

I suspect something wrong in Hub class or in DJ processing of SignalR Hub. Because there are nothing anyone full workable example in whole inet with strong typed Hub. Only small fragments of non accessible projects, even in this repository is exist non workable example with strong type Hub - strong type class is defined, but not using in project.

[BrennanConroy]

You are still defining your hub wrong. Please just copy paste this as your class definition: public class OutputMessages : Hub<IOutputMessages>

[ViacheslavUKR]

yes, thank you for your efforts. Finally connection is ON.

Message still not received for client, but maybe it's another problem with Blazor frontend or... I don't know what happens, I need more time.
But DJ container and SignalR Hub constructor now working correctly. And injection Hub to controller is working.
Thank you.