Error inserting host: Field 'authentication_string' doesn't have a default value

Update January 25, 2018:
An actual fix has been added to check for, and explicitly set the blank authentication_string value when adding an access host.
https://www.directadmin.com/features.php?id=2083

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old

Design change in MariaDB 10.2.x where DA is not specify a value for the authentication_string, when a host is set.
It might throw this error:

Error inserting host: Field 'authentication_string' doesn't have a default value

As a workaround, we can set a default value with this call SQL command:

ALTER TABLE mysql.user ALTER authentication_string SET DEFAULT '';

Run that sql in phpMyAdmin as the da_admin or root mysql Users.

Do not confuse this with MySQL 5.7, which uses the authentication_string to fully replace the password column.
For that, you'd tell DA to use mysql_milestone_16=1