'KernelEvents' not found issue

[Lyhtande]

Hello,
I get this error:
Error 1: Uncaught Error: Class 'forumhulp\errorpages\event\KernelEvents' not found in /var/www/vhosts/mydomain.com/httpdocs/archive/ext/forumhulp/errorpages/event/listener.php:134 Stack trace: #0 /var/www/vhosts/mydomain.com/httpdocs/archive/vendor/symfony/config/Resource/ReflectionClassResource.php(220): forumhulp\errorpages\event\listener::getSubscribedEvents() #1 /var/www/vhosts/mydomain.com/httpdocs/archive/vendor/symfony/config/Resource/ReflectionClassResource.php(117): Symfony\Component\Config\Resource\ReflectionClassResource->generateSignature(Object(ReflectionClass)) #2 /var/www/vhosts/mydomain.com/httpdocs/archive/vendor/symfony/config/Resource/ReflectionClassResource.php(66): Symfony\Component\Config\Resource\ReflectionClassResource->computeHash() #3 [internal function]: Symfony\Component\Config\Resource\ReflectionClassResource->serialize() #4 /var/www/vhosts/mydomain.com/httpdocs/archive/vendor/symfony/config/ResourceCheckerConfigCache.php(132): serialize(Array) #5 /var/ww at file /var/www/vhosts/mydomain.com/httpdocs/archive/ext/forumhulp/errorpages/event/listener.php line 134

phpBB: 3.3.5
PHP: 7.3.31
DB: MySQL(i) 10.4.21-MariaDB-1:10.4.21+maria~bionic
GZIP: enabled