Fatal error: Uncaught Error: Class "MailPoetVendor\Doctrine\ORM\Utility\IdentifierFlattener" not found in /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php:114
Stack trace:
#0 /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/doctrine/orm/lib/Doctrine/ORM/EntityManager.php(71): MailPoetVendor\Doctrine\ORM\UnitOfWork->__construct(Object(MailPoetVendor\Doctrine\ORM\EntityManager))
#1 /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/doctrine/orm/lib/Doctrine/ORM/EntityManager.php(445): MailPoetVendor\Doctrine\ORM\EntityManager->__construct(Object(MailPoet\Doctrine\SerializableConnection), Object(MailPoetVendor\Doctrine\ORM\Configuration))
#2 /htdocs/wp-content/plugins/mailpoet/lib/Doctrine/EntityManagerFactory.php(67): MailPoetVendor\Doctrine\ORM\EntityManager::create(Object(MailPoet\Doctrine\SerializableConnection), Object(MailPoetVendor\Doctrine\ORM\Configuration))
#3 /htdocs/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(646): MailPoet\Doctrine\EntityManagerFactory->createEntityManager()
#4 /htdocs/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(4908): MailPoetGenerated\FreeCachedContainer->getEntityManagerService()
#5 /htdocs/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(4898): MailPoetGenerated\FreeCachedContainer->getSettingsRepositoryService()
#6 /htdocs/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(2633): MailPoetGenerated\FreeCachedContainer->getSettingsController2Service()
#7 /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/symfony/dependency-injection/Container.php(122): MailPoetGenerated\FreeCachedContainer->getInitializerService()
#8 /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/symfony/dependency-injection/Container.php(110): MailPoetVendor\Symfony\Component\DependencyInjection\Container->make('MailPoet\\Config...', 1)
#9 /htdocs/wp-content/plugins/mailpoet/lib/DI/ContainerWrapper.php(39): MailPoetVendor\Symfony\Component\DependencyInjection\Container->get('MailPoet\\Config...')
#10 /htdocs/wp-content/plugins/mailpoet/mailpoet_initializer.php(89): MailPoet\DI\ContainerWrapper->get('MailPoet\\Config...')
#11 /htdocs/wp-content/plugins/mailpoet/mailpoet.php(194): require_once('/htdocs/wp-cont...')
#12 /htdocs/wp-settings.php(526): include_once('/htdocs/wp-cont...')
#13 /htdocs/wp-config.php(85): require_once('/htdocs/wp-sett...')
#14 /htdocs/wp-load.php(50): require_once('/htdocs/wp-conf...')
#15 /htdocs/wp-blog-header.php(13): require_once('/htdocs/wp-load...')
#16 /htdocs/index.php(17): require('/htdocs/wp-blog...')
#17 {main}
thrown in /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php on line 114