function civicrm_api3_mailing_event_subscribe_create($params) {
$email = $params['email'];
$group_id = $params['group_id'];
- $contact_id = CRM_Utils_Array::value('contact_id', $params);
+ $contact_id = $params['contact_id'] ?? NULL;
$group = new CRM_Contact_DAO_Group();
$group->is_active = 1;