Breaking: #96659 - Registration of cObjects via TYPO3_CONF_VARS

See forge#96659

Description

Since TYPO3 v12.0. custom Content Objects such as TEXT or HMENU are registered via the service configuration.

The previous way of registering custom Content Objects via $GLOBALS['TYPO3_CONF_VARS']['FE']['ContentObjects'] added in 7.2 (see forge#64386) has been removed.

Impact

TYPO3 installations using the previous way of registering custom or overridden Content Objects will not return the rendered frontend output for this specific Content Object anymore, which is a very rare case.

Affected Installations

TYPO3 installations with extensions registering custom Content Objects.

Migration

Extensions registering custom Content Objects should now use the service configuration:

MyCompany\MyPackage\ContentObject\CustomContentObject:
    tags:
        - name: frontend.contentobject
          identifier: 'MY_OBJ'

Extensions can be made compatible with TYPO3 v7 - v12 by keeping the "old" way of registration in ext_localconf.php and additionally add the new registration way, without any further changes.