How to fix Mysql table crashes

Whenever you enconter this:

Please use mysql_upgrade to fix this error.

or using  mysql_upgrade -u root -p says:

Looking for 'mysql' as: mysql
Looking for 'mysqlcheck' as: mysqlcheck
Error: Failed while fetching Server version! Could be due to unauthorized access.
FATAL ERROR: Upgrade failed

you can try this:

chown -R mysql /var/lib/mysql
mysql_upgrade -u root -p

来自为知笔记(Wiz)