<input class="required input-validation-error" data-val="true"
    data-val-required="Custom error message here" type="text"
    value="" id="Application_EducationReferences_0__Course"
    name="Application.EducationReferences[0].Course">

<span class="field-validation-error"
    data-valmsg-for="Application.EducationReferences[0].Course"
    data-valmsg-replace="true">
    <span for="Application_EducationReferences_0__Course" class="">
      This field is required.</span>
</span>

$("form").data("unobtrusiveValidation", null);
$("form").data("validator", null);
$.validator.unobtrusive.parse($("form"));