PHP Notice error _civicrm_add_formatted_param() on last page of csv contact import

This error appears on the last screen where the Done button is. The import looked like it succeeded.

Duplicate checking was disabled and the third date option was chosen.

Notice: Undefined index: custom in _civicrm_add_formatted_param() (line 368 of /home/shxxxxxx/shxxxxxx.com/html/sites/all/modules/civicrm/api/v2/utils.v2.php).