Validation type names in unobtrusive client validation rules must be unique

Question

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

Answer 1

In my case I had added both NotEmpty and Length conditions to the validation rules at the same time.

RuleFor(x => x.Code).NotEmpty().Length(1, 10);

When I removed the NotEmpty condition the error disappeared.