- When changing default MySQL database server in Tools & Settings > Database server > DB_server_hostname > Use this server as default for MySQL, default MySQL database server is not changed for a particular domain.
- A subscription to which this domain belongs is custom - service plan was set to None on its creation.
- Default MySQL database server for other domains which belong to subscriptions with a service plan is changed successfully.
This is expected behavior. When the subscription is customized, it has default database server which was set on the server during the subscription creation. It is not changed even if default database server is changed server-wide.
Connect to the server using SSH.
Unset the default MySQL database server for the affected subscription:
# plesk bin subscription_settings -u example.com -default_server_mysql none
Set the required MySQL database server as default for the affected subscription:
# plesk bin subscription_settings -u example. com -default_server_mysql 127.0.0.1:3306