Using Page Not Found in Extensions

Make sure ‘ErrorManagement.PageNotFound.View’ is defined on extension and refer the following code below

return Backbone.Router.extend({

routes: {
    'XYX/:id': 'XYZ',
}

,
initialize: function(application) {
    this.application = application;
},
XYZ: function(id) {
    var application = this.application;
    var list_id = JSON.stringify(id)
    var model = new CDSweepstakesModel();
    model.fetch({ data: { XYZ: list_id } }).done(function(result) {
        if(_.isEmpty(result)){
            var view = new PageNotFoundView({
                application: application
            });
            view.showContent();
        }
        else{
        var view = new CDSweepstakesSweepstakesView({ application: application, XYZ: result, listid: list_id })
        view.showContent();
        }
    });
}

});