In addition to that, I can't understand why modal windows every time is presenting once I click any button? And what is interesting the same and last, as an example, after failed login the message all time is popup when I clicking any button...

Hello,

You can refresh the login page. If the notifications are not removed after page load that mean there is something wrong with the session.

You can edit app/core/MY_Controller.php and add the lines below after line no 38 $meta['warning'] = $data['warning'] ?? $this->session->flashdata('warning');

$this->session->unset_userdata('error');
$this->session->unset_userdata('message');
$this->session->unset_userdata('warning');

These lines will reset the session messages data.

Thank you