Symptoms
When using the "MySQL Databases" interface of cPanel, you are not able to change the password for a MySQL user. You will be given the following error:
The request failed. (Error ID: kx78x3) Ask your hosting provider to research
this error in cPanel & WHM’s main error log.
Description
The error above indicates that there is an error taking place in the "mysql.global_priv" table within MySQL.
In MariaDB 10.4 and later, the "mysql.global_priv" table has replaced the "mysql.user" table.
If you are encountering the issue described above, you will see this error taking place in the log file, /usr/local/cpanel/logs/error_log
Cpanel::Exception::Database::Error/(XID kx78x3) The system received an error
from the “MySQL” database “mysql”: 1146 (Table 'mysql.global_priv' doesn't exist)
Workaround
First, take a backup of your MySQL databases:
How to backup MySQL databases before doing a MySQL upgrade
Then, run the following command to ensure your databases and tables are formatted properly for the new version of MariaDB:
mysql_upgrade