Update cursors and feature datasets

DaleRichter

Having a problem using an update cursor to add values to a field in a feature class that is in a feature dataset and has topology.  This code always works outside of a feature dataset and sometimes works inside a feature dataset without topology.

            UPDATE_FIELD = [error_field] + KEY_FIELD
            with arcpy.da.UpdateCursor (features, UPDATE_FIELD) as cursor:
                for row in cursor:
                    key = tuple (row [1:])
                    if key in error:
                        row [0] = error [key]
                        cursor.updateRow (row)
            del cursor

Any help would be appreciated. 

JoshuaBixby

If your feature class is in a feature dataset that has either a network or topology defined, then I believe you have to use an edit session, as the error indicates.