MySQL - Access denied for user 'root'@'localhost'

• Connect to mysql using below commands
  

• sudo su

• mysql

• Check if the user root is using mysql_native_password OR auth_socket

• SELECT user, host, authentication_string, plugin FROM mysql.user;

• It may have a blank value in authentication_string column and auth_socket in plugin column
• If that is the case, update user root with the following queries.

• ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'New-Root-Password';

• FLUSH PRIVILEGES;

That is all you need to do.