SQLSTATE[HY000] [2002] Connection refused

Typecho_Db_Adapter_Exception: SQLSTATE[HY000] [2002] Connection refused in /root/htdocs/hworld/var/Typecho/Db/Adapter/Pdo.php:60 Stack trace: #0 /root/htdocs/hworld/var/Typecho/Db.php(199): Typecho_Db_Adapter_Pdo->connect() #1 /root/htdocs/hworld/var/Typecho/Db.php(350): Typecho_Db->selectDb() #2 /root/htdocs/hworld/var/Typecho/Db.php(384): Typecho_Db->query() #3 /root/htdocs/hworld/var/Widget/Options.php(358): Typecho_Db->fetchAll() #4 /root/htdocs/hworld/var/Typecho/Widget.php(221): Widget_Options->execute() #5 /root/htdocs/hworld/var/Widget/Init.php(27): Typecho_Widget::widget() #6 /root/htdocs/hworld/var/Typecho/Widget.php(221): Widget_Init->execute() #7 /root/htdocs/hworld/admin/common.php(15): Typecho_Widget::widget() #8 /root/htdocs/hworld/admin/login.php(2): include('/root/htdocs/hw...') #9 {main}