Property mapping - DateTime to string and vice-versa mapping using Automapper in C#

Question

I have ASP.Net Core 2.1 C# application.

Below is my DTO

public class CustomerTO
{
 public int Id { get; set;}

 public DateTime SomeDate{get; set;}
}

Domain Class

public class Customer
{
 public int Id { get; set;}

 public string SomeDate{get; set;}
}

AutoMapper Class

public class ObjectsMapper
{
    private readonly IMapper _mapper;
    private const string _dateFormat = "yyyy’-‘MM’-‘dd’T’HH’:’mm’";

    public ObjectsMapper()
    {
        var config = new MapperConfiguration(cfg =>
        {

            cfg.CreateMap<Customer, CustomerTO>()

                .ForMember(dest => dest.SomeDate.ToString(_dateFormat), opt => opt.MapFrom(src => src.SomeDate))
                .ForMember(dest => dest.SomeDate.ToString(_dateFormat), opt => opt.MapFrom(src => src.SomeDate));

            cfg.CreateMap<CustomerTO, Customer>()

                   .ForMember(dest => dest.SomeDate, opt => opt.MapFrom(src => Convert.ToDateTime(src.SomeDate)))
                   .ForMember(dest => dest.SomeDate, opt => opt.MapFrom(src => Convert.ToDateTime(src.SomeDate)));

        });

        _mapper = config.CreateMapper();
    }

    public User Map(CustomerTO user) => _mapper.Map<CustomerTO, Customer>(customer);
}

But when the Map() is called from respective places, either it throws the below error or just stops the debugging/application with no error or output

[AutoMapperConfigurationException: Custom configuration for members is only supported for top-level individual members on a type.]

How do I handle this mapper (DateTime to String and vice-versa)?

Thanks!