Post input type text from bootstrap navbar to codeigniter controller
You must not have a form within a form: https://www.w3.org/TR/html5/forms.html#the-form-element
But you do that, because Codeigniter's echo form_open() creates a form tag - see form_open() - which you locate within your parent <form class="form-inline my-2 my-lg-0">. The second form will be ignored.
Resolve it with adding the classes as attributes to echo form_open():
$attr = array('class' => 'form-inline my-2 my-lg-0');echo form_open('users/modificaAzienda2', $attr);//....<?php echo form_close(); ?>