..  include:: /Includes.rst.txt

..  _important-108783-1737910000:

==================================================================
Important: #108783 - Backend user language default changed to "en"
==================================================================

See :issue:`108783`

Description
===========

The backend user language field (`be_users.lang`) historically used `default`
as the value for English. This has been changed to use the standard ISO 639-1
language code `en` instead.

The language key `default` is still accepted for backward compatibility with
custom code, but can no longer be selected in the backend user interface.

An upgrade wizard, `Migrate backend user language from 'default' to 'en'`,
is available to migrate existing backend user records.

Impact
======

*   New backend users have `en` as their default language instead of
    `default`.
*   Existing backend users with `lang=default` should run the upgrade wizard
    to migrate to `lang=en`.
*   In general, code that uses `default` as a language key (e.g. custom
    instances of :php:`LanguageService`) will continue to work, as
    `default` is still mapped to `en` internally.

..  index:: Backend, ext:core
