MediatR 3.0.1 Cannot get IAsyncRequestHandler working

I am getting the following error message when executing IRequest with IAsyncRequestHandler.

System.InvalidOperationException: 'No service for type 'MediatR.IRequestHandler`2[TestProject.Domain.Requests.Users.CreateUserRequest,TestProject.Domain.Requests.Users.CreateUserResponse]' has been registered.'

This is how i register it in the startup class

// Add framework services.
   services.AddMvc();                                                
   services.AddMediatR(typeof(CreateUserRequest).GetTypeInfo().Assembly);

CreateUserRequest and Response class

 public class CreateUserRequest : IRequest<CreateUserResponse>
    {
        public string EmailAddress { get; set; }
        public int OrganisationId { get; set; }
        public string Password { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }

public class CreateUserResponse
{
    public int UserId { get; set; }
    public string EmailAddress { get; set; }

}

Request handler class

public class CreateUserRequestHandler : IAsyncRequestHandler<CreateUserRequest, CreateUserResponse>
    {
        private readonly UserManager<User> _userManager;

       
        public CreateUserRequestHandler()
        {
           
        }

        public async Task<CreateUserResponse> Handle(CreateUserRequest request)
        {
            //create the user and assign it to the organisation
            var user = new User
            {
                Email = request.EmailAddress,
                OrganisationUsers = new List<OrganisationUser> { new OrganisationUser { OrganisationId = request.OrganisationId } }
            };

            //create new user with password.
            await _userManager.CreateAsync(user, request.Password);

            //create response.
            var response = new CreateUserResponse{UserId = user.Id, EmailAddress = user.Email};

            return response;
        }

Controller class

 public class UserController : Controller
    {
        private readonly IMediator _mediator;

        public UserController(IMediator mediator)
        {
            _mediator = mediator;
        }

        [HttpPost]
        public async Task<CreateUserResponse> Post(CreateUserRequest request)
        {
            return await _mediator.Send(request);
        }
    }

the error occurs inside the controller class it does not hit the async request handler.

Is there anything wrong with the DI registration? I have looked at the examples but could not find anything specific to aspnet core.

[ergincelik]

You can use this code in the startup.cs For example, there are 5 projects in your solution and you can use all of them

       public void ConfigureServices(IServiceCollection services)
      {
             Assembly.GetEntryAssembly().GetReferencedAssemblies()
                                                            .Where(c => c.FullName.StartsWith("App.")).ToList()
                                                           .ForEach(c => Assembly.Load(c.FullName));
      }

[MisiM]

My issue was that I had the query request and the response model in the Domain project and the query hander in the BusinessLogic project.