WP_Error: after registering new user

G’day everyone,
after I’ve made an update for the Ultimate Member — User Profile & Membership plugin I faced this problem. After I’m trying to register a new user – have this page:

http://joxi.ru/nAyG4kpIgEZNxm

with a code like:

array (
  'message' => 'Неверный ID пользователя.',
  'dump' => 
  array (
    'ID' => 
    WP_Error::__set_state(array(
       'errors' => 
      array (
        'empty_user_login' => 
        array (
          0 => 'Нельзя создать пользователя с пустым логином.',
        ),
      ),
       'error_data' => 
      array (
      ),
    )),
    'display_name' => ' ',
  ),
  'changes' => 
  array (
    'form_id' => '8931',

etc.

How can I fix this?

The page I need help with: [log in to see the link]