Breaking: #96982 - Removed support for global extensions
See forge#96982
Description
Historically, TYPO3 installations could load extensions from typo3/
where developers and site administrators could share extensions through
multiple installations on the same server via symlinks.
This feature was possible by enabling
$GLOBALS 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/ will be ignored in TYPO3 v12.0
and will be automatically disabled.
The global option to enable this feature will be removed from
Local 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/, which is unlikely in 2022.
Migration
It is recommended to either migrate to Composer Mode, or to use symlinks
into typo3conf/ (Local Extensions) to load the same extension for
multiple TYPO3 installations at once.