Cause
This error occurs if an attempt is made to access a property on an exclusive collection where the property is a subobject. This operation is not allowed.
This error is most-commonly caused if you add a subobject property (for example, slob, blob, or another collection) to one of your collection classes and then define an exclusive reference to this collection on another class. By making the reference exclusive, it becomes a subobject reference. Any attempt to use the subobjects on the collection from this reference will raise this error.
Action
Remove the subobject properties from the collection class, or make the reference to the collection a shared reference rather than an exclusive reference.