Issue with automapper in dotnet core webapi argument exception

[Poimen]

Hi,

Our project is using the start guide and mostly works as advertised. However, once we add automapper into the mix, we're facing an exception failure:

System.ArgumentException: GenericArguments[0], 'System.Int64', on 'T MaxFloat[T](System.Collections.Generic.IEnumerable`1[T])' violates the constraint of type 'T'.

The simple version of the models and config:

    public class C1 : IRequest<long>
    {
        public string FirstName { get; set; }
    }

    public class C2
    {
        public string FirstName { get; set; }
    }

    var mapperConfig = new MapperConfiguration(cfg => {
        cfg.CreateMap<C1, C2>();
    });
    IMapper mapper = mapperConfig.CreateMapper();
    services.AddSingleton(mapper);

The system throws the exception on cfg.CreateMap<C1, C2>();

If I remove IRequest<long> from the C1 model, all works as expected.

I can't work out why automapper does not like the IRequest interface. As far as I can tell, the IRequest is just a marker.

Have you ever seen this before?

[Poimen]

The typical one-last-search, and found the issue:
AutoMapper/AutoMapper#3988

Upgraded to v12, and fixed the issue.

Thanks 👍