I\'m setting up a new server and keep running into this problem.
When I try to login to the MySQL database with the root user, I get the error:
First step: go to /etc/phpmyadmin/config.inc.php then uncomment lines where you find AllowNoPassword . Second step: login to your mysql default account
mysql -u root -p use mysql; update user set plugin="" where user='root'; flush privilege;
and that's all!