Breaking: #96982 - Removed support for global extensions

See Issue #96982

Description

Historically, TYPO3 installations could load extensions from typo3/ext/ where developers and site administrators could share extensions through multiple installations on the same server via symlinks.

This feature was possible by enabling $GLOBALS[TYPO3_CONF_VARS][EXT][allowGlobalInstall] which was disabled by default since TYPO3 4.0, as using this feature had several downsides with Non-Composer based installations. Features such as “Automatic Updates” are not possible having this functionality enabled.

In Composer-based installations, this functionality was never supported in a proper way.

This functionality including the feature toggle have been removed in TYPO3 v12.0.

Impact

Extensions within the folder typo3/ext/ will be ignored in TYPO3 v12.0 and will be automatically disabled.

The global option to enable this feature will be removed from LocalConfiguration.php automatically once the Install Tool / Maintenance module is loaded the next time, if the option is activated.

Affected Installations

TYPO3 installations having the global option enabled, and have loaded extensions in typo3/ext/, which is unlikely in 2022.

Migration

It is recommended to either migrate to Composer Mode, or to use symlinks into typo3conf/ext/ (Local Extensions) to load the same extension for multiple TYPO3 installations at once.