session error in codeigniter?

when I want to set session data in codeigniter 3 it says error like:

A PHP Error was encountered

Severity: Warning

Message: mkdir(): Invalid path

Filename: drivers/Session_files_driver.php

Line Number: 117

Backtrace:

File: C:xampphtdocsci-testapplicationcontrollerslogin.php
Line: 7
Function: __construct

File: C:xampphtdocsci-testindex.php
Line: 292
Function: require_once

Here is the code that where want to set session data.

$sess_array = array(
         'id' => 1,
         'username' => 'bikramkc.kc@gmail.com'
       );
$this->session->set_userdata($sess_array);

Sharing a solution that helped me, try set your config variable like:

$config['sess_save_path'] = sys_get_temp_dir();

This error comes when we use directory bases session approach in CodeIgniter. If we use database based session approach error will go. Use code below –

change your application->config->config.php and set

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

& Run SQL query

CREATE TABLE IF NOT EXISTS `ci_sessions` (
        `id` varchar(40) NOT NULL,
        `ip_address` varchar(45) NOT NULL,
        `timestamp` int(10) unsigned DEFAULT 0 NOT NULL,
        `data` blob NOT NULL,
        PRIMARY KEY (id),
        KEY `ci_sessions_timestamp` (`timestamp`)
);

In config.php sess_save_path should be sys_get_temp_dir(); then it will resolve the error of mkdir(): Invalid path

The reason you encountered the error is because you didn’t have a $config['sess_save_path']

Go to you config.php and set

$config['sess_save_path'] = NULL;

1.Open the config.php on application/config folder

2.Browse all the way down to the $config['sess_save_path'] = NULL; line.

3.Change the NULL value to BASEPATH.'sessions'

It can be due to PHP and codeIgniter version.
For me, PHP 7.1.25 and CI 3.0.4 didn’t work. You can check with session_id(). Session was refreshed.
With CI 3.1.2 it works.

Try this in your config.php
$config['sess_save_path'] = NULL

1. Use absolute path for $config['sess_save_path'] in config file.
2. Point it to your writable temporary directory.
3. Make sure the directory is under the directory allowed in apache or nginx config.

If $config['sess_save_path'] is sys_get_temp_dir() then session data will store in system folder.

And If you have database table as ci_sessions with below config.php:

$config['sess_driver'] = 'database';
$config['sess_cookie_name'] = 'ci_session';

The data will store in database. In this case you can $config['sess_save_path'] = NULL;

I had a similar case I have a multihost in godaddy and first I corrected the .htacces file

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteBase / 

    RewriteCond %{REQUEST_URI} ^system.*
    RewriteRule ^(.*)$ /index.php?/$1 [L]

    RewriteCond %{REQUEST_URI} ^application.*
    RewriteRule ^(.*)$ /index.php?/$1 [L]

    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php?/$1 [L]
</IfModule>

<IfModule !mod_rewrite.c> 
    ErrorDocument 404 /index.php
</IfModule>

Then correct the file config.php

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