GridViewCell.Errors - System.Collections.IEnumerable Errors { set; get; }

Errors collection always returns a collection of strings.  When using .NET 4.5 and INotifyDataErrorInfo the errors can be any type. In our case we are using a custom ValidationResult object that has different severity levels.

Because GridViewCell.Errors always returns strings and not the original underlying ValidationResult object our DataTemplate for ValidationResult is not applied.