If you are unable to create database users in Plesk and displaying the errors as follows upon creation:
Error: Connection to the database server has failed:
Table ‘mysql.servers’ doesn’t exist
This error generally occurs while compiling MySQL to new version, apparently due to incomplete MySQL upgrade.
So give the following from shell as root to solve the issue.
mysql_fix_privilege_tables --user=admin --password=<admin password> --verbose
Replace <admin password> with the exact password
That will fix all issues!
Thank you,