By default, Plesk ships with the username root replaced with admin and the passworded is stored in a shadow file. As such, you will need to create a new MySQL account with the root privileges.
Log in to your Plesk server with SSH and connect to MySQL using the following command:
Create the MySQL user. Replace YOURPASSWORD with a unique string and store this password securely.
CREATE USER 'ywhbackup'@'localhost' IDENTIFIED BY 'YOURPASSWORD'; GRANT ALL PRIVILEGES ON * . * TO 'ywhbackup'@'localhost'; FLUSH PRIVILEGES;
Now your MySQL server is configured with the username ywhbackup. Use this username and the chosen password to enable MySQL backup in R1soft.