I have a custom page that copies items from one list in one site to another, and its failing with the exception above.

I tried checking the field using sharepoint  manager but I didnt find anything strange.  The field where its failing its a managed metadata column the strange thing its that the exception is shown when checking if the field[internalname] is != null

  

      foreach (SPListItem item in listItems)
                                    {
                                        SPListItem targetItem = destinationList.Items.Add();
                                        foreach (SPField field in item.Fields)
                                        {
                                            if (!field.ReadOnlyField && field.InternalName !="Attachments")
                                            {
                                                if (item[field.InternalName] != null)
                                                {