环境：
centos 6.5
mysql 5.5.20 升级 5.6.25 报错：
mysql升级报错：
mysql.time_zone_transition_type OK
mysql.user OK
Running 'mysql_fix_privilege_tables'...
Running 'mysqlcheck with default connection arguments
/usr/local/mysql/bin/mysqlcheck: Got error: 1045: Access denied for user 'root'@'localhost' (using password: NO) when trying to connect
FATAL ERROR: Upgrade failed
[root@t1 mysql-5.6.25]# /usr/local/mysql/bin/mysql_upgrade -uroot -p
Enter password:
Looking for 'mysql' as: /usr/local/mysql/bin/mysql
拍错过程：
[root@t1 mysql-5.6.25]# /usr/local/mysql/bin/mysql_upgrade -uroot -p
Enter password:
Looking for 'mysql' as: /usr/local/mysql/bin/mysql
Looking for 'mysqlcheck' as: /usr/local/mysql/bin/mysqlcheck
FATAL ERROR: Upgrade failed
[root@t1 mysql-5.6.25]# mysql -uroot -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
[root@t1 mysql-5.6.25]# mysql -uroot -p123456
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
[root@t1 mysql-5.6.25]# mysql -uroot -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
[root@t1 mysql-5.6.25]# ps -ef | grep mysqld
存在 3306
[root@t1 mysql-5.6.25]# mysql -uroot -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
[root@t1 mysql-5.6.25]# find / -name mysql.sock
/var/lib/mysql/mysql.sock
/usr/local/mysql/mysql.sock
[root@t1 mysql-5.6.25]# ln -s /usr/local/mysql/mysql.sock /var/lib/mysql/mysql.sock
ln: creating symbolic link `/var/lib/mysql/mysql.sock': File exists
[root@t1 mysql-5.6.25]# ll /var/lib/mysql/mysql.sock
lrwxrwxrwx 1 root root 15 Mar 3 13:12 /var/lib/mysql/mysql.sock -> /tmp/mysql.sock
[root@t1 mysql-5.6.25]# rm /var/lib/mysql/mysql.sock
rm: remove symbolic link `/var/lib/mysql/mysql.sock'? y
[root@t1 mysql-5.6.25]# mysql -uroot -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
解决办法：
[root@t1 mysql-5.6.25]# ln -s /usr/local/mysql/mysql.sock /var/lib/mysql/mysql.sock
[root@t1 mysql-5.6.25]# mysql -uroot -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
说明密码错误。
赠送：
SELECT host FROM mysql.user WHERE User = 'root';问题解决
[root@t1 mysql-5.6.25]# mysql -uroot -p123456
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 21
Server version: 5.6.25 Source distribution
Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select @@version;
+-----------+
| @@version |
+-----------+
| 5.6.25 |
+-----------+
1 row in set (0.00 sec)
mysql> exit
Bye
