---
title: "Important: #108783 - Backend user language default changed to \"en\""
manual: "TYPO3 Core Changelog"
version: "main"
permalink: "https://docs.typo3.org/permalink/changelog:important-108783-1737910000"
source: "Changelog/14.2/Important-108783-BackendUserLanguageDefaultChangedToEn.rst"
typo3-version: "14.2"
typo3-major: 14
type: "important"
issue: 108783
forge: "https://forge.typo3.org/issues/108783"
tags: ["Backend", "ext:core"]
rendered: "2026-09-20T18:31:11+00:00"
---

# Important: #108783 - Backend user language default changed to "en" {#important-108783-1737910000}

See [forge#108783](https://forge.typo3.org/issues/108783)

## Description {#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 {#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 `LanguageService`) will continue to work, as
    `default` is still mapped to `en` internally.