ERROR 2013 (HY000): Lost connection to MySQL server during query
查看报错日志如下：tail -fn 30 /var/log/mysqld.log
2017-10-25 12:56:22 112085 [ERROR] Missing system table mysql.proxies_priv; please run mysql_upgrade to create it
2017-10-25 12:56:22 112085 [ERROR] Native table 'performance_schema'.'cond_instances' has the wrong structure
2017-10-25 12:56:22 112085 [ERROR] Native table 'performance_schema'.'events_waits_current' has the wrong structure
2017-10-25 12:56:22 112085 [ERROR] Native table 'performance_schema'.'events_waits_history' has the wrong structure
2017-10-25 12:56:22 112085 [ERROR] Native table 'performance_schema'.'events_waits_history_long' has the wrong structure

    看报错日志一直在提示wrong structure（结构错误），通常结构错误是由升级MySQL版本导致的，虽然没有升级，但是在安装MySQL5.6.22前，安装的是5.1版本，可能是由于卸除的不干净也会导致
 

解决方法

   执行升级脚本命令：

/usr/local/mysql/bin/mysql_upgrade -u root -p

输入密码后回车，再次赋权成功