django3.0开始LANGUAGE_CODE前面必须配相应的LANGUAGES配置如下：
from django.utils.translation import gettext_lazy as _
LANGUAGES = [ (‘zh-Hans‘, _(‘Chinese‘)), ] LANGUAGE_CODE = ‘zh-Hans‘
(translation.E004) You have provided a value for the LANGUAGE_CODE setting that is not in the LANGUAGES setting.
原文：https://www.cnblogs.com/dhcn/p/12038629.html
