Fatal error: Uncaught Error: Class 'Neos\Flow\Core\Migrations\AbstractMigration' not found in /var/www/vhosts/www.thomas-bartholomaeus.de/content/neoscms/Packages/Application/Neos.Neos.Ui/Migrations/Code/Version20180907103800.php:17 Stack trace: #0 {main} thrown in /var/www/vhosts/www.thomas-bartholomaeus.de/content/neoscms/Packages/Application/Neos.Neos.Ui/Migrations/Code/Version20180907103800.php on line 17