Could not load file or assembly 'System.Web.Helpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies

public class GlobalResourceTypeResourceDataAnnotationsModelValidator : DataAnnotationsModelValidator<ValidationAttribute>
{
    public GlobalResourceTypeResourceDataAnnotationsModelValidator(
        ModelMetadata metadata, 
        ControllerContext context, 
        ValidationAttribute attribute
    )
        : base(metadata, context, attribute)
    {
        if (Attribute.ErrorMessageResourceType == null)
        {
            Attribute.ErrorMessageResourceType = typeof(ModelValidationMessages);
        }
    }
}

DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(RequiredAttribute), 
    typeof(GlobalResourceTypeResourceDataAnnotationsModelValidator));
DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(StringLengthAttribute), 
   typeof(GlobalResourceTypeResourceDataAnnotationsModelValidator));

JSON.stringify(whole_object)