Error after update to Joomla 5.0

-- HikaShop version -- : 5.0.0
-- Joomla version -- : 5.0.0
-- PHP version -- : 8.1.25
-- Browser(s) name and version -- : Chrome
-- Error-message(debug-mod must be tuned on) -- : Event onContentBeforeDisplay only accepts String results.

STARTSEITE
Call Stack
# Function Location
1 () JROOT/libraries/src/Event/Result/ResultTypeStringAware.php:67
2 Joomla\CMS\Event\Content\BeforeDisplayEvent->typeCheckResult() JROOT/libraries/src/Event/Result/ResultAware.php:64
3 Joomla\CMS\Event\Content\BeforeDisplayEvent->addResult() JROOT/libraries/src/Plugin/CMSPlugin.php:297
4 Joomla\CMS\Plugin\CMSPlugin->Joomla\CMS\Plugin\{closure}() JROOT/libraries/vendor/joomla/event/src/Dispatcher.php:454
5 Joomla\Event\Dispatcher->dispatch() JROOT/components/com_content/src/View/Article/HtmlView.php:248
6 Joomla\Component\Content\Site\View\Article\HtmlView->display() JROOT/libraries/src/MVC/Controller/BaseController.php:697
7 Joomla\CMS\MVC\Controller\BaseController->display() JROOT/components/com_content/src/Controller/DisplayController.php:122
8 Joomla\Component\Content\Site\Controller\DisplayController->display() JROOT/libraries/src/MVC/Controller/BaseController.php:730
9 Joomla\CMS\MVC\Controller\BaseController->execute() JROOT/libraries/src/Dispatcher/ComponentDispatcher.php:143
10 Joomla\CMS\Dispatcher\ComponentDispatcher->dispatch() JROOT/components/com_content/src/Dispatcher/Dispatcher.php:56
11 Joomla\Component\Content\Site\Dispatcher\Dispatcher->dispatch() JROOT/libraries/src/Component/ComponentHelper.php:361
12 Joomla\CMS\Component\ComponentHelper::renderComponent() JROOT/libraries/src/Application/SiteApplication.php:218
13 Joomla\CMS\Application\SiteApplication->dispatch() JROOT/libraries/src/Application/SiteApplication.php:261
14 Joomla\CMS\Application\SiteApplication->doExecute() JROOT/libraries/src/Application/CMSApplication.php:306
15 Joomla\CMS\Application\CMSApplication->execute() JROOT/includes/app.php:58
16 require_once() JROOT/index.php:32

Hi,
i get the following error, when i update to Joomla 5.0