I assume once you add another your new language URL works but the original URLs does not work? Once you have more than 1 language then your original URL should have a language identifier. 

For example, your original Url is https://test.com/news

You have added a new language (let's say DE) - The new language url will be https://de.test.com/news or https://test.com/de/news (depends how you have setup in Manage websites/host settings)

Now your original url https://test.com/news gives you 404

The new "original" URL will be https://test.com/en/news 

if you specify default culture (let's say en) then your https://test.com/news will works as well

Hi,

Thanks for responding. /Register is a custom route to create users in ASPNet Identity. It doesn't have a corresponding CMS page item in Episerver CMS. So, it is not the same as /news or en/news. I tried with en/register, that throws 404 too. The default language is set to en. All our CMS pages work without any problem.

The out of the box register page created in Alloy is specifically for the creation of the first admin user. The register page itself has a check in the Business/AdministrationRegisterPage.cs class to if it's enabled such as if a user is register and if it's a local request. They might be blocking the page from loading so you'll have to adapt this logic if you need to use it

See the authorization check in the RegisterController class

        protected override void OnAuthorization(AuthorizationContext filterContext)
        {
            if (!AdministratorRegistrationPage.IsEnabled)
            {
                filterContext.Result = new HttpNotFoundResult();
                return;
            }
            base.OnAuthorization(filterContext);
        }