Schließe ich mich direkt mal an. Gleiches Problem hier auch:
Doctrine\ORM\ORMInvalidArgumentException: EntityManager#detach() expects parameter 1 to be an entity object, NULL given. in /vendor/doctrine/orm/lib/Doctrine/ORM/ORMInvalidArgumentException.php:189 Stack trace:
#0 /vendor/doctrine/orm/lib/Doctrine/ORM/EntityManager.php(656): Doctrine\ORM\ORMInvalidArgumentException::invalidObject('EntityManager#d...', NULL)
#1 /engine/Shopware/Controllers/Frontend/Forms.php(161): Doctrine\ORM\EntityManager->detach(NULL)
#2 /engine/Shopware/Controllers/Frontend/Forms.php(73): Shopware_Controllers_Frontend_Forms->getContent('5')
#3 /engine/Library/Enlight/Controller/Action.php(192): Shopware_Controllers_Frontend_Forms->indexAction()
#4 /engine/Library/Enlight/Controller/Dispatcher/Default.php(478): Enlight_Controller_Action->dispatch('indexAction')
#5 /engine/Library/Enlight/Controller/Front.php(228): Enlight_Controller_Dispatcher_Default->dispatch(Object(Enlight_Controller_Request_RequestHttp), Object(Enlight_Controller_Response_ResponseHttp))
#6 /engine/Shopware/Kernel.php(185): Enlight_Controller_Front->dispatch()
#7 /vendor/symfony/http-kernel/HttpCache/SubRequestHandler.php(102): Shopware\Kernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#8 /vendor/symfony/http-kernel/HttpCache/HttpCache.php(448): Symfony\Component\HttpKernel\HttpCache\SubRequestHandler::handle(Object(Shopware\Kernel), Object(Symfony\Component\HttpFoundation\Request), 1, true)
#9 /engine/Shopware/Components/HttpCache/AppCache.php(256): Symfony\Component\HttpKernel\HttpCache\HttpCache->forward(Object(Symfony\Component\HttpFoundation\Request), true, NULL)
#10 /vendor/symfony/http-kernel/HttpCache/HttpCache.php(420): Shopware\Components\HttpCache\AppCache->forward(Object(Symfony\Component\HttpFoundation\Request), true)
#11 /vendor/symfony/http-kernel/HttpCache/HttpCache.php(317): Symfony\Component\HttpKernel\HttpCache\HttpCache->fetch(Object(Symfony\Component\HttpFoundation\Request), true)
#12 /engine/Shopware/Components/HttpCache/AppCache.php(183): Symfony\Component\HttpKernel\HttpCache\HttpCache->lookup(Object(Symfony\Component\HttpFoundation\Request), true)
#13 /vendor/symfony/http-kernel/HttpCache/HttpCache.php(192): Shopware\Components\HttpCache\AppCache->lookup(Object(Symfony\Component\HttpFoundation\Request), true)
#14 /engine/Shopware/Components/HttpCache/AppCache.php(110): Symfony\Component\HttpKernel\HttpCache\HttpCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#15 /var/www/vhosts/jr-werbemittel.de/httpdocs/shopware.php(122): Shopware\Components\HttpCache\AppCache->handle(Object(Symfony\Component\HttpFoundation\Request))
#16
Bist du mit deinem Problem weiter gekommen.
Das sollte am Cache liegen. Habe aber selbst noch nicht rausgefunden woran es genau liegt