Symptoms

After migrating to new code (workflow and forms), most old active instances are unable to be actioned. The workflow was modified to consolidate 2 activities into 1 activity (with a different name)..

Migrating the old processes to the newest version of the workflow is causing a null reference error indicating not set to an instance of an object.

 

Diagnoses

Due to the workflow modification was done in such a way that ProcessInstanceVersionMigrator which is using Process Instance Management API cannot support. For more detail on support and unsupported scenarios, please see http://help.k2.com/onlinehelp/k2blackpearl/devref/4.6.7/Important_Notes.html
 

Resolution

Inserting 2 activities/events (named identical to the ones that were removed) to act as "stubs" in the workflow so that the workflow activity rules can be added back into the form. The process will never use these activities based on line rules so all new instances will utilize the new consolidated activity. Once the old process instances are completed, the stub activities and corresponding form rules can be safely removed from the form.