Class "JError" not found

=13pxHallo, ich habe das Update Joomla 3 auf Joomla 4 gemacht. Nun bekomme ich folgenden Fehler in Frontend. Ich hatte schon mal die Joomla 4 ganz neu installiert, aber für ein anderes Projekt. Auf der Seite lief alles wie gewohnt. Es scheint also im Zusammenhang mit dem Update zu stehen.Über Hilfe wäre ich dankbar. LG und DankeCall stack#FunctionLocation1()JROOT/plugins/content/jw_sig/jw_sig.php:2362plgContentJw_sig->renderSimpleImageGallery()JROOT/plugins/content/jw_sig/jw_sig.php:473plgContentJw_sig->onContentPrepare()JROOT/libraries/src/Plugin/CMSPlugin.php:2854Joomla\CMS\Plugin\CMSPlugin->Joomla\CMS\Plugin\{closure}()JROOT/libraries/vendor/joomla/event/src/Dispatcher.php:4865Joomla\Event\Dispatcher->dispatch()JROOT/libraries/src/Application/EventAware.php:1116Joomla\CMS\Application\WebApplication->triggerEvent()JROOT/components/com_content/src/View/Article/HtmlView.php:2407Joomla\Component\Content\Site\View\Article\HtmlView->display()JROOT/libraries/src/MVC/Controller/BaseController.php:6928Joomla\CMS\MVC\Controller\BaseController->display()JROOT/components/com_content/src/Controller/DisplayController.php:1259Joomla\Component\Content\Site\Controller\DisplayController->display()JROOT/libraries/src/MVC/Controller/BaseController.php:73010Joomla\CMS\MVC\Controller\BaseController->execute()JROOT/libraries/src/Dispatcher/ComponentDispatcher.php:14611Joomla\CMS\Dispatcher\ComponentDispatcher->dispatch()JROOT/components/com_content/src/Dispatcher/Dispatcher.php:5512Joomla\Component\Content\Site\Dispatcher\Dispatcher->dispatch()JROOT/libraries/src/Component/ComponentHelper.php:38913Joomla\CMS\Component\ComponentHelper::renderComponent()JROOT/libraries/src/Application/SiteApplication.php:20614Joomla\CMS\Application\SiteApplication->dispatch()JROOT/libraries/src/Application/SiteApplication.php:24515Joomla\CMS\Application\SiteApplication->doExecute()JROOT/libraries/src/Application/CMSApplication.php:27816Joomla\CMS\Application\CMSApplication->execute()JROOT/includes/app.php:6317require_once()JROOT/index.php:32

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