Fatal error: Uncaught Error: Undefined constant PDO::MYSQL_ATTR_USE_BUFFERED_QUERY in /var/www/html/includes/database/mysql/database.inc:334
Stack trace:
#0 /var/www/html/includes/database/database.inc(1808): DatabaseConnection_mysql->__construct(Array)
#1 /var/www/html/includes/database/database.inc(1582): Database::openConnection('default', 'default')
#2 /var/www/html/includes/database/database.inc(2699): Database::getConnection()
#3 /var/www/html/includes/cache.inc(359): db_escape_table('cache_bootstrap')
#4 /var/www/html/includes/cache.inc(340): DrupalDatabaseCache->getMultiple(Array)
#5 /var/www/html/includes/cache.inc(57): DrupalDatabaseCache->get('module_implemen...')
#6 /var/www/html/includes/module.inc(763): cache_get('module_implemen...', 'cache_bootstrap')
#7 /var/www/html/includes/module.inc(963): module_implements('system_theme_in...')
#8 /var/www/html/modules/system/system.module(2531): module_invoke_all('system_theme_in...')
#9 /var/www/html/includes/theme.inc(798): _system_rebuild_theme_data()
#10 /var/www/html/includes/theme.maintenance.inc(57): list_themes()
#11 /var/www/html/includes/bootstrap.inc(2965): _drupal_maintenance_theme()
#12 /var/www/html/includes/errors.inc(177): drupal_maintenance_theme()
#13 /var/www/html/includes/bootstrap.inc(2690): _drupal_log_error(Array, true)
#14 [internal function]: _drupal_exception_handler(Object(Error))
#15 {main}
  thrown in /var/www/html/includes/database/mysql/database.inc on line 334