无法连接数据库 ERROR: SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket 已解决悬赏5积分

情况：

一直正常使用，今天重启服务器后无法连接数据库。

日志：

15:23:25 ERROR: SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in framework/base/router.class.php on line 2164, last called by framework/base/router.class.php on line 2115 through function connectByPDO.

 in framework/base/router.class.php on line 2215 when visiting

其他操作：

登录数据库 没问题

禅道配置 没问题。