JQuery Ajax call gives 404 'Resource Not Found' Error but normal URL call is fine

Instead of hard-coding the URL, you might want to try a UrlHelper:

$(function() {
    $("#username").click(function() {
        var url = '<%= UrlHelper.Action("GetSoftwareChoice", "ViewRecord") %>';
        $.getJSON(url, {username: '123'}, function(data) {
            alert(data);
        });
    });
});

I fix this problem by using FireBug to show me the request that was generated by JQuery. To my amazement, the url generated is

http://localhost/ViewRecord/ViewRecord/GetSoftwareChoice?username=123

for the JSON call:

$(function() {
$("#username").click(function() {
        $.getJSON("ViewRecord/GetSoftwareChoice", {username:'123'},
    function(data) {
        alert(data);
    });
    });
});

So I just have to change the $.getJSON line to

$.getJSON("GetSoftwareChoice", {username:'123'},

Alternatively, use the forward slash:

 $.getJSON("/ViewRecord/GetSoftwareChoice", {username:'123'},

$(function() {
    $("#username").click(function() {
        $.getJSON('<%= Url.Action("GetSoftwareChoice", "ViewRecord")%>',{username: '123'}, function(data) {
            alert(data);
        });
    });
});