Jonathan – my guess is that you have a [Required] attribute on one of your models. You would need to remove it and handle it with fluent validation code. Hope it helps!

“Additional information: Validation type names in unobtrusive client validation rules must be unique. The following validation type was seen more than once: required”

Where should I look to fix this?

That would be inherited from PropertyValidator. You can checkout fluentvalidation at GitHub . Here’s PropertyValidator: https://github.com/JeremySkinner/FluentValidation/blob/master/src/FluentValidation/Validators/PropertyValidator.cs


var formatter = new MessageFormatter().AppendPropertyName(Rule.GetDisplayName());
string message = formatter.BuildMessage(RequiredIfClientSideValidator.ErrorMessageSource.GetString());


What does RequiredIfClientSideValidator.ErrorMessageSource look like?