Server upload file error

Change your code to this and see if you get the same results.

PHP Code:

$targetDir = FCPATH . '/xyz_xrh/documenti_personali/'.session('user_id'); 


Also what type of sessions are you running file, database etc;

i use file , can i set : 

Code:

$sessionExpiration = 0; 

to prevent ?in this way if browser is open $this->session->get('user_id') is set until the user  close browser