AutoMapper - Cannot map between IdentityUser subclass and its correspondant DTO - asp.net

Question

I'm working on a project with asp.net core and Identity,
I am trying to create a mapping configuration between IdentityUser subclasse and its correspondant DTO using Automapper
I have done similar configuration with other classes and it works fine, but with IdentityUser subclass it behaves differently :
Here is my IdentityUser subclasse :
public partial class Collaborateur : IdentityUser
{
public Collaborateur() : base()
{
this.Activites = new HashSet<ActiviteCollaborateur>();
this.ActeursAvantVente = new HashSet<ActeurAvv>();
}
public string Nom { get; set; }
public string Prenom { get; set; }
public string Telephone { get; set; }
public Nullable<long> Matricule { get; set; }
public string Structure { get; set; }
public string Login { get; set; }
public RoleEnum Role { get; set; }
public virtual ICollection<ActiviteCollaborateur> Activites { get; set; }
public virtual ICollection<ActeurAvv> ActeursAvantVente { get; set; }
public virtual Agence Agence { get; set; }
public DateTime CreatedAt { get; set; }
public DateTime LastModified { get; set; }
}
Its corresponding DTO :
public class CollaborateurDTO : BaseDTO
{
public string Nom { get; set; }
public string Prenom { get; set; }
public string Telephone { get; set; }
public Nullable<long> Matricule { get; set; }
public string Structure { get; set; }
public string Login { get; set; }
public RoleEnum Role { get; set; }
}
CollaborateurProfile config class :
public class CollaborateurProfile : Profile
{
CollaborateurProfile()
{
CreateMap<Collaborateur, CollaborateurDTO>().ReverseMap();
CreateMap<Collaborateur, Collaborateur>()
.ForMember(x => x.Id, opt => opt.Ignore())
.ForMember(x => x.CreatedAt, opt => opt.Ignore())
.ForMember(x => x.LastModified, opts => opts.MapFrom(src => DateTime.UtcNow));
}
}
and Startup.cs :
services.AddAutoMapper();
it stops at this line with
MissingMethodException was unhandled by user code
An exception of type 'System.MissingMethodException' occurred in System.Private.CoreLib.ni.dll but was not handled in user code

Answer 1

By mistake i answered this question at the question linked in the comments (https://stackoverflow.com/a/46567611/7131186)
Here is my answer:
In my case (and it seems that this is your case too) it was a copy/paste problem. I somehow ended up with a PRIVATE constructor for my mapping profile:
using AutoMapper;
namespace Your.Namespace
{
public class MappingProfile : Profile
{
MappingProfile()
{
CreateMap<Animal, AnimalDto>();
}
}
}
(take note of the missing "public" in front of the ctor)
which compiled perfectly fine, but when AutoMapper tries to instantiate the profile it can't (of course!) find the constructor!