In the new version of MySQL (or MariaDB) user 'root' can not connect to the database server through PhpMyAdmin. To solve this problem perform the following actions.

[root@kvmde54-19861 ~]# mysql -V
mysql Ver 15.1 Distrib 5.5.60-MariaDB, for Linux (x86_64) using readline 5.1

Connect to the database server as root user in the terminal and use 'mysql' database:  
mysql -u root -p mysql  

Change the 'plugin' value for the 'root' user in the 'users' table:
MariaDB [mysql]> update user set
plugin='' where user='root'

Set privileges:  
MariaDB [mysql]&gt  
flush privileges  

If you want to go back to disabling root access from anything other than the shell, you can follow the same steps, but in the second step change the value of "plugin" to "unix_socket".
update user set
plugin='unix_socket' where user='root'


Updated May 12, 2020