jQuery validation: change default error message

This worked for me:

// Change default JQuery validation Messages.
$("#addnewcadidateform").validate({
        rules: {
            firstname: "required",
            lastname: "required",
            email: "required email",
        },
        messages: {
            firstname: "Enter your First Name",
            lastname: "Enter your Last Name",
            email: {
                required: "Enter your Email",
                email: "Please enter a valid email address.",
            }
        }
    })

You can specify your own messages in the validate call. Lifting and abbreviating this code from the Remember the Milk signup form used in the Validation plugin documentation (http://jquery.bassistance.de/validate/demo/milk/), you can easily specify your own messages:

var validator = $("#signupform").validate({
    rules: {
        firstname: "required",
        lastname: "required",
        username: {
            required: true,
            minlength: 2,
            remote: "users.php"
        }
    },
    messages: {
        firstname: "Enter your firstname",
        lastname: "Enter your lastname",
        username: {
            required: "Enter a username",
            minlength: jQuery.format("Enter at least {0} characters"),
            remote: jQuery.format("{0} is already in use")
        }
    }
});

The complete API for validate(...) : http://jqueryvalidation.org/validate

This worked for me:

$.validator.messages.required = 'required';

Add this code in a separate file/script included after the validation plugin to override the messages, edit at will :)

jQuery.extend(jQuery.validator.messages, {
    required: "This field is required.",
    remote: "Please fix this field.",
    email: "Please enter a valid email address.",
    url: "Please enter a valid URL.",
    date: "Please enter a valid date.",
    dateISO: "Please enter a valid date (ISO).",
    number: "Please enter a valid number.",
    digits: "Please enter only digits.",
    creditcard: "Please enter a valid credit card number.",
    equalTo: "Please enter the same value again.",
    accept: "Please enter a value with a valid extension.",
    maxlength: jQuery.validator.format("Please enter no more than {0} characters."),
    minlength: jQuery.validator.format("Please enter at least {0} characters."),
    rangelength: jQuery.validator.format("Please enter a value between {0} and {1} characters long."),
    range: jQuery.validator.format("Please enter a value between {0} and {1}."),
    max: jQuery.validator.format("Please enter a value less than or equal to {0}."),
    min: jQuery.validator.format("Please enter a value greater than or equal to {0}.")
});