Fatal error: Uncaught Error: Class "Zikula\Bundle\CoreInstallerBundle\Event\CoreInstallerBundleEvent" not found in /home/dwtechco/public_html/vendor/zikula/coreinstaller-bundle/Event/CoreUpgradePreExtensionUpgrade.php:20 Stack trace: #0 {main} thrown in /home/dwtechco/public_html/vendor/zikula/coreinstaller-bundle/Event/CoreUpgradePreExtensionUpgrade.php on line 20