Symptoms

We are getting the following error from a K2 Designer for SharePoint process calling a K2 Studio process from the "Call Sub-Process" event:

28042 IPC Failed to Start: 28031 Xmlfield ItemReferences not found

This is happening only for newly created processes (all old processes created pre-upgrade to 4.6.10 are working). This also happens on more than one site collection. Different sub-process calls work without error.
 

Diagnoses

This was identified as a breaking change and a bug was logged. To workaround the issue:

a. Create an "ItemReferences" XmlField on the Process that is being IPC'ed to
b. Redeploy this Process
c. Repair the IPC Start error
 

Resolution

This issue has been logged to be resolved in a future update.