---
title: "Deprecation: #99882 - Site language \"typo3Language\" setting"
manual: "TYPO3 Core Changelog"
version: "main"
permalink: "https://docs.typo3.org/permalink/changelog:deprecation-99882-1675873624"
source: "Changelog/12.3/Deprecation-99882-SiteLanguageTypo3LanguageSetting.rst"
typo3-version: "12.3"
typo3-major: 12
type: "deprecation"
issue: 99882
forge: "https://forge.typo3.org/issues/99882"
tags: ["YAML", "NotScanned", "ext:core"]
rendered: "2026-09-17T21:17:42+00:00"
---

# Deprecation: #99882 - Site language "typo3Language" setting {#deprecation-99882-site-language-typo3language-setting}

See [forge#99882](https://forge.typo3.org/issues/99882)

## Description {#description}

A language configuration defined for a site has had various settings, one of
them being `typo3Language`. The setting is used to define the language key which
should be used for fetching the proper XLF file (such as `de_AT.locallang.xlf`).

Since TYPO3 v12 it is unnecessary to set this property in the site configuration
and it is removed from the backend UI. The information is now automatically
derived from the `locale` setting of the site configuration.

The previous value "default", which matched "en" as language key is now unnecessary
as "default" is now a synonym for "en".

As a result, the amount of options in the user interface for integrators is
reduced.

## Impact {#impact}

An administrator cannot select a value for the `typo3Language` setting anymore
via the TYPO3 backend. If a custom value is required, the site configuration
needs to be manually edited and the `typo3Language` setting needs to be added.

If this is the case, please file a bug report in order to give the TYPO3
development team feedback on what use case is required.

However, saving a site configuration via the TYPO3 backend will still
keep the `typo3Language` setting so no values will be lost.

## Affected installations {#affected-installations}

TYPO3 installations created before TYPO3 v12.3.

## Migration {#migration}

No migration is needed as the explicit option is still evaluated. It is however
recommended to check if the setting is really necessary.

Examples:

1.  If `typo3Language: "default"` and `locale: "en_US.UTF-8"`, the setting can be removed.
1.  If `typo3Language: "pt_BR"` and `locale: "pt_BR.UTF-8"`, the setting can be removed.
1.  If `typo3Language: "de"` and `locale: "de_AT.UTF-8"` , the setting can be removed,
    plus the label files check for `de_AT.locallang.xlf` and `de.locallang.xlf`
    as fallback when accessing a translated label.
1.  If `typo3Language: "pt_BR"` and `locale: "de_DE.UTF-8"` it is likely
    a misconfiguration in the setup, and should be analyzed if the custom value is really needed.