Feature: #84581 - Introduce Site Handling

See forge#84581


Site Handling has been added to TYPO3.

Its goal is to make managing multiple sites easier to understand and faster to do. Sites bring a variety of new concepts to TYPO3 which we will explain below.

Take your time and read through the entire document since some concepts rely on each other.

typo3conf/sites folder

New sites will live in the folder typo3conf/sites/. In the first iteration this folder will contain a file called config.yaml which holds all configuration for a given site.

Note that if you are using a composer based installation, then the file location is <project-root>/config/sites/<identifier>/config.yaml

In the future this folder can (and should) be used for more files like Fluid templates, and Backend layouts.


# the rootPage Id (see below)
rootPageId: 12
# my base domain to run this site on. It either accepts a fully qualified URL or "/" to react to any domain name
base: 'https://www.example.com/'
# The language array
    # the TYPO3 sys_language_uid as you know it since... ever
    languageId: '0'
    # The internal name for this language. Unused for now, but in the future this will affect display in the backend
    title: English
    # optional navigation title which is used in HMENU.special = language
    navigationTitle: ''
    # Language base. Accepts either a fully qualified URL or a path segment like "/en/".
    base: /
    # sets the locale during frontend rendering
    locale: en_US.UTF-8
    # two-letter code for the language according to ISO-639 nomenclature (see https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes)
    iso-639-1: en
    # FE href language
    hreflang: en-US
    # FE text direction
    direction: ltr
    # Language Identifier to use in localLang XLIFF files
    typo3Language: default
    # Flag Identifier
    flag: gb
    languageId: '1'
    title: 'danish'
    navigationTitle: Dansk
    base: /da/
    locale: da_DK.UTF-8
    iso-639-1: da
    hreflang: da-DK
    direction: ltr
    typo3Language: default
    flag: dk
    fallbackType: strict
    languageId: '2'
    title: Deutsch
    navigationTitle: ''
    base: 'https://www.beispiel.de'
    locale: de_DE.UTF-8
    iso-639-1: de
    hreflang: de-DE
    direction: ltr
    typo3Language: de
    flag: de
    # Enable content fallback
    fallbackType: fallback
    # Content fallback mode (order is important)
    fallbacks: '2,1,0'
# Error Handling Array (order is important here)
# Error Handlers will check the given status code, but the special value "0" will react to any error not configured
# elsewhere in this configuration.
    # HTTP Status Code to react to
    errorCode: '404'
    # The used ErrorHandler. In this case, it's "Display content from Page". See examples below for available options.
    errorHandler: Page
    # href to the content source to display (accepts both fully qualified URLs as well as TYPO3 internal link syntax
    errorContentSource: 't3://page?uid=8'
    errorCode: '403'
    errorHandler: Fluid
    # Path to the Template File to show
    errorFluidTemplate: 'EXT:my_extension/Resources/Private/Templates/ErrorPages/403.html'
    # Optional Templates root path
    errorFluidTemplatesRootPath: 'EXT:my_extension/Resources/Private/Templates/ErrorPages'
    # Optional Layouts root path
    errorFluidLayoutsRootPath: 'EXT:my_extension/Resources/Private/Layouts/ErrorPages'
    # Optional Partials root path
    errorFluidPartialsRootPath: 'EXT:my_extension/Resources/Private/Partials/ErrorPages'
    errorCode: '0'
    errorHandler: PHP
    # Fully qualified class name to a class that implements PageErrorHandlerInterface
    errorPhpClassFQCN: Vendor\ExtensionName\ErrorHandlers\GenericErrorhandler

All settings can also be edited via the backend module Site Management > Configuration.

Keep in mind that due to the nature of the module, comments or additional values in your config.yaml file will get deleted on saving.

site identifier

The site identifier is the name of the folder within typo3conf/sites/ that will hold your configuration file(s). When choosing an identifier make sure to stick to ASCII but you may also use -, _ and . for convenience.


Root pages are identified by one of these two properties:

  • they are direct descendants of PID 0 (the root root page of TYPO3)
  • they have the "Use as Root Page" property in pages set to true.


The new backend module relies on FormEngine to render the edit interface. Since the form data is not stored in database records but in .yml files, a couple of details have been extended of the default FormEngine code.

The render configuration is stored in typo3/sysext/backend/Configuration/SiteConfiguration/ in a format syntactically identical to TCA. However, this is not loaded into $GLOBALS['TCA'] scope, and only a small subset of TCA features is supported.

Extending site configuration is experimental and may change any time.

In practice the configuration can be extended, but only with very simple fields like the basic config type input, and even for this one not all features are possible, for example the eval options are limited. The code throws exceptions or just ignores settings it does not support. While some of the limits may be relaxed a bit over time, many will be kept. The goal is to allow developers to extend the site configuration with a couple of simple things like an input field for a Google API key. However it is not possible to extend with complex TCA like inline relations, database driven select fields, Flex Form handling and similar.

The example below shows the experimental feature adding a field to site in an extensions file Configuration/SiteConfiguration/Overrides/sites.php. Note the helper methods of class TYPO3\CMS\core\Utility\ExtensionManagementUtility can not be used.

// Experimental example to add a new field to the site configuration

// Configure a new simple required input field to site
$GLOBALS['SiteConfiguration']['site']['columns']['myNewField'] = [
    'label' => 'A new custom field',
    'config' => [
        'type' => 'input',
        'eval' => 'required',
// And add it to showitem
$GLOBALS['SiteConfiguration']['site']['types']['0']['showitem'] = str_replace(
    'base, myNewField, ',

The field will be shown in the edit form of the configuration module and it's value stored in the .yaml file. Using the site object TYPO3\CMS\core\Site\Entity\Site, the value can be fetched using ->getConfiguration()['myNewField'].


The following TypoScript settings will be set based on config.yaml rather than needing to have them in your TypoScript template:

  • config.language
  • config.htmlTag_dir
  • config.htmlTag_langKey
  • config.sys_language_uid
  • config.sys_language_mode
  • config.sys_language_isocode
  • config.sys_language_isocode_default

Links to pages within a site can now be generated via any access of TYPO3, so in both BE and FE as well as CLI mode.