Localization Not Working For New Universal Login Page Template

Last Updated: Sep 10, 2025

Overview

When customizing the New Universal Login with Page Templates, the locale variable does not appear to be changing to match the language being used in the browser. The locale variable is intended to be used to render the login pages, matching one of the supported tenant languages

Cause

If you are using a custom domain configuration was done with a self-managed certificate, your reverse proxy (which handles the custom domain TLS) may not be forwarding the Accept-Language header to Auth0. This would result in the preferred language from the browser not making it to the Page Template variable.

Solution

Review your reverse proxy configuration and confirm that is forwarding the Accept-Language header to Auth0. You can then test with your page template to confirm that the locale variable is being updated:

<!DOCTYPE html><html lang="{{locale}}">