This occurs if the fields have not been mapped on the import. 

To resolve: 
  1. From any module, go to Administration > Import Records
  2. Choose the type of import you are currently working with
  3. Click New Import or choose a saved parameter. 
  4. Set any necessary options on the general tab, including the import file location.
  5. Navigate to the fields tab
  6. Click Update Fields to automatically map import fields. 
  7. Map any remaining fields manually
  8. Click Import Now or Validate Now