Fatal error: Uncaught Error: Class "MailPoet\Util\Notices\HeadersAlreadySentNotice" not found in /htdocs/wp-content/plugins/mailpoet/lib/Util/Notices/PermanentNotices.php:80 Stack trace: #0 /htdocs/wp-content/plugins/mailpoet/generated/FreeCachedContainer.php(2276): MailPoet\Util\Notices\PermanentNotices->__construct(Object(MailPoet\WP\Functions), Object(MailPoet\Settings\TrackingConfig), Object(MailPoet\Subscribers\SubscribersRepository), Object(MailPoet\Settings\SettingsController), Object(MailPoet\Util\License\Features\Subscribers), Object(MailPoet\Config\ServicesChecker), Object(MailPoet\Mailer\MailerFactory)) #1 /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/symfony/dependency-injection/Container.php(122): MailPoetGenerated\FreeCachedContainer->getInitializerService() #2 /htdocs/wp-content/plugins/mailpoet/vendor-prefixed/symfony/dependency-injection/Container.php(110): MailPoetVendor\Symfony\Component\DependencyInjection\Container->make('MailPoet\\Config...', 1) #3 /htdocs/wp-content/plugins/mailpoet/lib/DI/ContainerWrapper.php(39): MailPoetVendor\Symfony\Component\DependencyInjection\Container->get('MailPoet\\Config...') #4 /htdocs/wp-content/plugins/mailpoet/mailpoet_initializer.php(89): MailPoet\DI\ContainerWrapper->get('MailPoet\\Config...') #5 /htdocs/wp-content/plugins/mailpoet/mailpoet.php(206): require_once('/htdocs/wp-cont...') #6 /htdocs/wp-settings.php(462): include_once('/htdocs/wp-cont...') #7 /htdocs/wp-config.php(96): require_once('/htdocs/wp-sett...') #8 /htdocs/wp-load.php(50): require_once('/htdocs/wp-conf...') #9 /htdocs/wp-blog-header.php(13): require_once('/htdocs/wp-load...') #10 /htdocs/index.php(17): require('/htdocs/wp-blog...') #11 {main} thrown in /htdocs/wp-content/plugins/mailpoet/lib/Util/Notices/PermanentNotices.php on line 80