I cannot create subscription, the following error is shown in the Task Manager:
Foreign key 'plesk_hosts_fk0' violation while executing' INSERT INTO plesk_hosts(sub_id, referer, host_id, ipv4 ) VALUES ( ? , ? , ? , ? )'
The issue is caused by Service Template misconfiguration: the subscription contains IIS webspace and Apache webspace resources. Such configuration is not supported by PPA 11.1, "Multiple Webspaces" feature was implemented in PPA 11.5.
Remove Apache or IIS webspace resource from the Service Template and then recreate subscription.