Breaking: #96899 - "displayWarningMessages" hook removed 

See forge#96899

Description 

The hook $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_befunc.php']['displayWarningMessages'] has been removed in favor of a new PSR-14 event \TYPO3\CMS\Backend\Controller\Event\ModifyGenericBackendMessagesEvent .

The hook was used to display messages in the About module.

Impact 

Registered hooks are not executed anymore.

Affected Installations 

TYPO3 installations with custom extensions using this hook, which is very unlikely. The extension scanner will report possible usages.

Migration 

The hook is removed without deprecation in order to allow extensions to work with TYPO3 v11 (using the hook) and v12+ (using the new event).

Use the PSR-14 event as a direct replacement.