setting rootURL causing 404 error on page refresh

Question

If I set language as rootURL this works I am able to go to any route/subroute and current language will be present in url, but on page refresh browser is trying get app from that language folder any thoughts? :/ I am using Ember 1.11.

// router.coffee

`import Ember from 'ember';`
`import config from './config/environment';`

Router = Ember.Router.extend
  location: config.locationType
  rootURL: '/' + localStorage.getItem('locale') + '/'

// config/environment.js

module.exports = function(environment) {
  var ENV = {
    locationType: 'history',
    baseURL: '/'
...

Answer 1

You shouldn't use rootURL for this purpose. Instead, create a route that will be a parent to all other routes:

//../app/router.js

import Ember from 'ember';
import config from './config/environment';
var Router = Ember.Router.extend(
    {
        location: config.locationType
    }
);
Router.map(
    function ()
    {
        this.route(
            'lang', { path: '/:lang' }, function ()
            {
                this.route('index', { path: '/' });
                this.route('404', { path: '/*wildcard' });
                this.route('your-route-name');
            }
        );
    }
);
export default Router;

Than you can use afterModel method of lang route to determine desired locale:

//../app/routes/lang.js
import config from '../config/environment';
export default Ember.Route.extend(
    {
        afterModel: function (params)
        {
            var allowedLocales = config.i18n.allowedLocales;
            var defaultLocale = config.i18n.defaultLocale;
            this.set(
                'i18n.locale',
                params && params.lang && allowedLocales.indexOf(params.lang) > -1 ? params.lang : defaultLocale
            );
        }
    }
);

And in index route you need to detect user's locale from browser's settings or use default one:

//../app/routes/index.js
import config from '../config/environment';
export default Ember.Route.extend(
    {
        beforeModel: function ()
        {
            var allowedLanguages = config.i18n.allowedLocales;
            var language = config.i18n.defaultLocale;
            if (navigator.languages) {
                for (let lang of navigator.languages) {
                    if (allowedLanguages.indexOf(lang) > -1) {
                        language = lang;
                        break;
                    }
                }
            } else {
                if (navigator.language) {
                    language = navigator.language;
                } else {
                    if (navigator.userLanguage) {
                        language = navigator.userLanguage;
                    }
                }
            }
            this.transitionTo('lang.index', { lang: language });
        }
    }
);

BTW, your Ember version is quite old. You may want to upgrade it to 1.13 (1.13.x shouldn't break your app, 2.x could).