Symptoms
Navigation OA > Services > WebHosting Plesk > Service Nodes is impossible:
An unexpected error occurred. Please try again later.
Cause
There are some inconsistencies at reply of "/hosts" method at http://www.parallels.com/pa/pa-core-services/host-management/1
resource, some nodes do not have aps.id property. The issue is caused by the bug with id #POA-111047 (""host-management" returns several nodes without "aps.id" property").
Resolution
Change the Ready to provide
option (switch from "ready to provide" to "not ready to provide" and back) for the nodes that were added to OA before OSA 7.0.