Symptoms

While attempting to deploy a P&D package to the target environment, the post-deployment check showed many items from the package with an error like:
"Cannot insert duplicate key row in object 'Form.Control' with unique index 'UX_Form_Control_ViewID_FormID_Name'. The duplicate key value is ..."

At this point, P&D becomes unresponsive.
 

Diagnoses

Customer restarted the K2 server, and deployment was successful.

We think the following sequence of events happened:
-In the target environment one of the forms was checked out
-P&D did not look for checked out forms in the target environment
-Some sort of deadlock condition occurred in P&D due to the checked out form, causing it to freeze but keeping open the db connection and lock
-Subsequent retries of P&D were blocked
-A restart killed the connection
-The form was checked in
-P&D Worked
 

Resolution

Restart the K2 server, and retry P&D deployment.