Fatal error: Uncaught Error: Undefined class constant 'MYSQL_ATTR_USE_BUFFERED_QUERY' in D:\wamp64\www\drupal\includes\database\mysql\database.inc:334 Stack trace: #0 D:\wamp64\www\drupal\includes\database\database.inc(1796): DatabaseConnection_mysql->__construct(Array) #1 D:\wamp64\www\drupal\includes\database\database.inc(1582): Database::openConnection('default', 'default') #2 D:\wamp64\www\drupal\includes\database\database.inc(2687): Database::getConnection() #3 D:\wamp64\www\drupal\includes\cache.inc(359): db_escape_table('cache_bootstrap') #4 D:\wamp64\www\drupal\includes\cache.inc(340): DrupalDatabaseCache->getMultiple(Array) #5 D:\wamp64\www\drupal\includes\cache.inc(57): DrupalDatabaseCache->get('module_implemen...') #6 D:\wamp64\www\drupal\includes\module.inc(763): cache_get('module_implemen...', 'cache_bootstrap') #7 D:\wamp64\www\drupal\includes\module.inc(963): module_implements('system_theme_in...') #8 D:\wamp64\www\drupal\modules\system\system.module(2531): module_invoke_all('system_theme_in...') #9 D:\wamp in D:\wamp64\www\drupal\includes\database\mysql\database.inc on line 334