DisableConstructorMapping.cs

static void Main(string[] args)
{
  // Setup Mapper config
  var config = new MapperConfiguration(c =>
  {
      c.DisableConstructorMapping();

      c.CreateMap<RoleDTO, Role>();

      c.CreateMap<UserDTO, User>()
      .ForMember(entity => entity.Roles, opt => opt.Ignore());
  });
  // Validate Mapper config
  config.AssertConfigurationIsValid();

  // Test class that gets mapper by DI
  var test = new Test(config.CreateMapper());
  test.StartTest();
}

public class Test
{
   IMapper Mapper;

   public Test(IMapper mapper)
   {
       Mapper = mapper;
   }

   public void StartTest()
   {
       var sourceRoleDTO = new RoleDTO() { Name = "TestRole" };
       var sourceUserDTO = new UserDTO
       {
           Name = "TestUser",
           Email = "[email protected]",
           Roles = new List<RoleDTO>() { sourceRoleDTO }
       };

       var role = Mapper.Map<Role>(sourceRoleDTO);
       var user = Mapper.Map<User>(sourceUserDTO);
   }

}

public class RoleDTO
{
   public string Name { get; set; }
   public RoleDTO() { }
}

public class UserDTO
{
   public string Name { get; set; }
   public string Email { get; set; }
   public ICollection<RoleDTO> Roles { get; set; }
   public UserDTO() { }
}

public class Role
{
   public string Name { get; set; }

   public Role() { }
}

public class User
{
   public string Name { get; set; }
   public string Email { get; set; }
   public ICollection<Role> Roles { get; set; }
   public User()
   {
       Roles = new List<Role>();
	   Console.WriteLine("Ok");
   }

   public User(string name, string email, ICollection<Role> roles) : this()
   {
   		Console.WriteLine("Wrong");
       // SHOULD NOT USE THIS CONSTRUCTOR!!!
       foreach (Role r in roles)
           Roles.Add(r);
   }

}