You can only connect to root account for both MySQL and MariaDB if you are logged in to the system as root user or by using sudo. If not, you will get access denied error even if you entered correct password for your root MySQL account. 

$ mysql -u root -p Enter password:  ERROR 1698 (28000): Access denied for user 'root'@'localhost'

Steps to connect to root MySQL / MariaDB account from normal user:

  1. Connect to MySQL / MariaDB as root or other administrative user account. 

    $ sudo mysql -u root -p [sudo] password for user:  Enter password:  Welcome to the MySQL monitor.  Commands end with ; or \g. Your MySQL connection id is 45 Server version: 8.0.22-0ubuntu0.20.10.2 (Ubuntu)  Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.  Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners.  Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.  mysql>

  2. Configure root user to use mysql_native_password authentication plugin. 

    Amysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY //; Query OK, 0 rows affected (0.01 sec)

    Change localhost and password accordingly.

  3. Reload the grant tables for MySQL / MariaDB server. 

    mysql> FLUSH PRIVILEGES; Query OK, 0 rows affected (0.00 sec)

  4. Log in again to root MySQL / MariaDB account from normal system account to test. 

    $ mysql -u root Welcome to the MySQL monitor.  Commands end with ; or \g. Your MySQL connection id is 46 Server version: 8.0.22-0ubuntu0.20.10.2 (Ubuntu)  Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.  Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners.  Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.  mysql>