mariadb Error 1045: Access denied for user 'root'@'localhost' (using password: YES) code example

Example 1: access denied for user 'root'@'localhost' mariadb

UPDATE mysql.user SET plugin = 'mysql_native_password' WHERE user = 'root' AND plugin = 'unix_socket';
FLUSH PRIVILEGES;

Example 2: Error 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

sudo mysql -u root -p