Add Database button is missing from Subscriptions > example.com > Manage in Customer Panel > Databases:
The number of available database resources is set to Unlimited in Subscriptions > example.com > Account > Resources:
Database server selection is switched off in Subscriptions > example.com > Account > Permissions:
- Cannot select database type while creating it
Only default database servers are available for the selection.
MySQL default database server is set to None in Service Plans > Default > Hosting Parameters > Default Database Server:
Default MySQL server is absent and/or there is no permission to select it.
Log in to Plesk and apply one of the following:
Enable Database server selection directive in Service Plans > Default > Permissions > Show more available permissions and press Update & Sync:
Switch MySQL default database server from None to localhost:3306 in Service Plans > Default > Hosting Parameters > Default Database Server and press Update & Sync:
Note: it is also applicable to cases when Amazon RDS extension is installed. If it is needed to provide customer with the ability to select Amazon server, enable "database server selection" option.