Mysql 启动失败：Fatal error: mysql.user table is damaged

症状

Mysql5.1卸载后重装5.7 服务无法启动。

查看/var/log/mysqld.log日志提示：

[ERROR] Fatal error: mysql.user table is damaged. Please run mysql_upgrade.

原因

重装5.7后没有运行 mysql_upgrade

解决方法

1.在/etc/my.cnf中[mysqld] 下面添加skip-grant-tables

 [mysqld]

# Remove leading # and set to the amount of RAM for the most important data

# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.

# innodb_buffer_pool_size = 128M

# Remove leading # to turn on a very important data integrity option: logging

# changes to the binary log between backups.

# log_bin

# Remove leading # to set options mainly useful for reporting servers.

# The server defaults are faster for transactions and fast SELECTs.

# Adjust sizes as needed, experiment to find the optimal values.

# join_buffer_size = 128M

# sort_buffer_size = 2M

# read_rnd_buffer_size = 2M

datadir=/var/lib/mysql

socket=/var/lib/mysql/mysql.sock

skip-grant-tables

2.启动mysql服务

# service mysqld start

3.运行更新命令

#  mysql_upgrade

4.在/etc/my.cnf中删除skip-grant-tables

5.重启mysql服务

# service mysqld restart