Symptoms

Seeing the following error on process instances after upgrading to 4.6.9
ERROR - One or more field types are not installed properly. Go to the list settings page to delete these fields
 

Diagnoses

Found that the filter on a SmartObject was referring to a field not associated with the list. Apparently this was allowed in 4.6.8.

 

Resolution

Correct the filter in the SmartObject, resolved the issue.