Message: unlink(/tmp/ci_sessionaa51644b4360c8f6957d2c733): Operation not permitted

@arma7x here is my config.php Session Variables section

$config['sess_driver'] = 'files';
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_save_path'] = NULL;
$config['sess_match_ip'] = FALSE;
$config['sess_time_to_update'] = 300;
$config['sess_regenerate_destroy'] = FALSE;

I think i have to use database driver then no path will be defined and give permission to any folder, am i correct?

$config['sess_save_path'] must be defined according to the driver you are using. In the case of the files driver, it must be an absolute path to a writable directory. In the case of the database driver, it must be the name of a table in your database which has been created with the structure outlined in the user guide.

You will almost always run into errors if sess_save_path is NULL.

Bonfire

Practical CodeIgniter 3
CodeIgniter Testing Guide