Warning: Class "Drupal\Core\Http\KernelEvent" not found in /var/www/html/vendor/drupal/core/includes/bootstrap.inc on line 135
Fatal error: Uncaught Error: Class "Symfony\Component\EventDispatcher\Event" not found in /var/www/html/vendor/drupal/core/lib/Drupal/Component/EventDispatcher/Event.php:15
Stack trace:
#0 /var/www/html/vendor/composer/ClassLoader.php(576): include()
#1 /var/www/html/vendor/composer/ClassLoader.php(427): Composer\Autoload\{closure}('/var/www/html/v...')
#2 /var/www/html/vendor/drupal/core/lib/Drupal/Core/Http/KernelEvent.php(20): Composer\Autoload\ClassLoader->loadClass('Drupal\\Componen...')
#3 /var/www/html/vendor/composer/ClassLoader.php(576): include('/var/www/html/v...')
#4 /var/www/html/vendor/composer/ClassLoader.php(427): Composer\Autoload\{closure}('/var/www/html/v...')
#5 [internal function]: Composer\Autoload\ClassLoader->loadClass('Drupal\\Core\\Htt...')
#6 /var/www/html/vendor/drupal/core/includes/bootstrap.inc(135): class_alias('Drupal\\Core\\Htt...', 'Symfony\\Compone...', true)
#7 /var/www/html/vendor/composer/autoload_real.php(45): require('/var/www/html/v...')
#8 /var/www/html/vendor/composer/autoload_real.php(49): {closure}('2f69d3914119f04...', '/var/www/html/v...')
#9 /var/www/html/vendor/autoload.php(25): ComposerAutoloaderInit53591a0dcfb0444605a3fe11287fe0b6::getLoader()
#10 /var/www/html/autoload.php(16): require('/var/www/html/v...')
#11 /var/www/html/index.php(14): require_once('/var/www/html/a...')
#12 {main}
thrown in /var/www/html/vendor/drupal/core/lib/Drupal/Component/EventDispatcher/Event.php on line 15