find() and findAll() issues

Given the following code:

Code:

   $cond = array('id'=>'id', 'lang'=>'lang');
   $ret = $this->model->where($cond)->findAll();
or
   $cond = array('lang'=>'lang');
   $ret = $this->model->where($cond)->find('id');

Both code above working very well when using Google Chrome browser, however return anything (crashes) in all other browsers (IExplorer, Firefox, Edges).

Also, without 'where' clause the code working in all browsers.

Any idea about the issue?

infos: windows 10-64, MariaDB 10.3.15, PHP 7.3.6, CI 4.1.5.

Thanks.