./Mysql-bin.index 'not found (errcode: 13) Solution

Prompt. /The mysql-bin.index cannot be found (because MySQL has enabled the bin log function), to the database root directory to view the file is there, may be a file permission problem, the permission for viewing the root directory of the database is 700, and the owner and user group are both root. It may be that the folder permission was accidentally modified when the database was last transferred.
Solution:
Chgrp-r mysql./var & chown-r mysql./var (here the root directory of the database is/*****/var)
Restart MySQL [OK]