Hi, There is an issue with Taiwanese locale at least in Horizon. It would be good to get a feedback from i18n team according to OpenStack docs too. Speaking about Horizon, Chinese locales were renamed in Django 1.7 [1]. Zh-cn became zh-Hans, and zh-tw became zh-Hant. Old names were marked as deprecated and finally removed in Django 1.11. Current supported Django versions are 1.11 and 2.0 [2] It is not an issue for Chinese because django locale middleware does silent fallback from zh-cn to zh-Hans. But for Taiwanese it treats zh-tw as some unknown variant of zh-* and also does fallback to default zh-cn, which is wrong. Reported bug: https://bugs.launchpad.net/horizon/+bug/1830886 Proposed solution is to migrate to new locale names everywhere in Horizon. Here are proposed steps to fix this issue: 1. Zanata jobs reconfiguration 2. Django-related backend stuff. Biggest, but easiest part because it is well documented 3. AngularJS. Quite old version is used, so we can hit some well forgotten issues. Also, testing is complicated. 4. Horizon.js components. It is the smallest part Other question will be thorougful testing of the bugfix. [1] https://docs.djangoproject.com/en/dev/releases/1.7/#language-codes-zh-cn-zh-... [2] https://docs.openstack.org/horizon/latest/install/system-requirements.html