Breaking: #109811 - Removed "afterFormStateInitialized" hook 

Description 

The hook $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['ext/form']['afterFormStateInitialized'] has been removed in favor of the PSR-14 event \TYPO3\CMS\Form\Event\AfterFormStateInitializedEvent .

In addition, the interface \TYPO3\CMS\Form\Domain\Runtime\FormRuntime\Lifecycle\AfterFormStateInitializedInterface has been removed as it was only used by the hook.

Impact 

Hook implementations registered under afterFormStateInitialized are no longer executed in TYPO3 v15.0 and later.

Classes implementing \TYPO3\CMS\Form\Domain\Runtime\FormRuntime\Lifecycle\AfterFormStateInitializedInterface will cause a PHP fatal error.

Affected installations 

TYPO3 installations with custom extensions using this hook or implementing AfterFormStateInitializedInterface are affected.

The extension scanner reports any usage as a strong match.

Migration 

Register a PSR-14 event listener for \TYPO3\CMS\Form\Event\AfterFormStateInitializedEvent instead:

use TYPO3\CMS\Core\Attribute\AsEventListener;
use TYPO3\CMS\Form\Event\AfterFormStateInitializedEvent;

#[AsEventListener(identifier: 'my-extension/after-form-state-initialized')]
final readonly class MyAfterFormStateInitializedEventListener
{
    public function __invoke(AfterFormStateInitializedEvent $event): void
    {
        // Access $event->formRuntime->getFormState() here
    }
}

Remove the hook registration from ext_localconf.php and the AfterFormStateInitializedInterface implementation from your hook class.

See also the Feature entry.