Symptoms

ERROR - SharePoint Document Copy with Add a Document to this Content Field checked.
 

Diagnoses

We are receiving error Server was unable to process request. ---> Object reference not set to an instance of an object for a step in a couple of workflows that include a step to copy a SharePoint Document from one library to another.

It seems to occur only when we have 'Add a Document to this Content Field" checked. If I uncheck it works.

When I hover over the Content Field that was used using Create - it shows XML Field, Scope=Process
Value : where previously showed as
XML Field, Scope=Process XPath=/ Value :
 

Resolution

Labs support team has linked this ticket to a tfs item. A suggested workaround is to change the Preserve metada checkbox on the wizard to True.