C# Model validation throws “Cannot convert from System.DateTime to System.Array”

Question

I'm trying to insert to a table from excel using LinqToExcel and when I call

ValidateModel(u);

It throws an exception:

Cannot convert from System.DateTime to System.Array

I'm using DataAnnotations on the viewmodel.

Datetime in ViewModel:

[DisplayFormat(DataFormatString = "{0:dd-MM-yyyy}", ApplyFormatInEditMode = true)]
public DateTime FECHA_ADQ { get; set; }

Controller:

foreach (var a in excel.Worksheet<ViewModel>(sheet.First())) 
{
    //Validations//
    try 
    {
        Context db = new Context();
        ViewModel u = a;
        ModelState.Clear();
        ValidateModel(u);

        //Insert//
    }
    catch(Exception)
    {
        // ...
    }
}

Datetime in excel file:

This is what it looks like on the debugger:

Answer 1

I couldn't resolve the issue with excel so i just ended up validating after the mapping to the base model and it worked.

ModelState.Clear();

var config = new MapperConfiguration(cfg => {
    cfg.CreateMap<ViewModel, Model>();
});

IMapper mapper = config.CreateMapper();
var inv = mapper.Map<ViewModel, Model>(u);

if (inv.FECHA_ADQ.Year <= 2005) {
    errors.AppendLine("Serial: " + a.SERIAL + " Error on Row: " + row + " Cause: Invalid Date.");
    counter++;
} else {
    ValidateModel(inv);
    Context.ModelDB.Add(inv);
    Context.SaveChanges();
}