Fatal error: Uncaught Error: Class "Drupal\Core\Database\Schema" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php:17 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php on line 17