Deprecation: #92494 - Extbase EnvironmentService

See Issue #92494

Description

The extbase class TYPO3\CMS\Extbase\Service\EnvironmentService is an API for TYPO3’s legacy constant TYPO3_MODE. That constant has been marked as deprecated in v11 and superseded by core API class TYPO3\CMS\Core\Http\ApplicationType, which relies on a PSR-7 request to determine frontend or backend mode. The EnvironmentService has now been marked as deprecated as a logical follow-up to these works.

Impact

Using the class will trigger a PHP E_USER_DEPRECATED error.

Affected Installations

Even though TYPO3\CMS\Extbase\Service\EnvironmentService is @internal, some extensions may still rely on it. The extension scanner will find usages.

Migration

Instances with extensions using that class should either make their code agnostic to frontend or backend mode, or use ApplicationType. Code examples can be found in the Changelog file.