Ajax getting 400 Bad Request when submitting Form only on Firefox

Solution:

Try this

$('form[name="contact-me"]').submit(function (e) {
        e.preventDefault();

        var form = $('#form_id')[0]; //set form id

        var varform = new FormData(form);

        varform.append("action", "zt_save_campain_form_data");

        $.ajax({
            url: ajaxurl,
            type: 'POST',
            dataType: 'json',
            data: varform,
            processData: false,
            contentType: false,
            cache: false,
            crossDomain: true,
            success: function (response) {

              //if success do this...
             console.log(response);

            },

            error: function (xhr, textStatus, error) {
                console.log(xhr, textStatus, error);
            }

        })

    });

Inside your form you can put this code for nonce validation

<?php wp_nonce_field( 'name_of_my_action', 'name_of_nonce_field' ); ?>