The cause for the Unwritable message for PHP session save path is pretty straight forward, that’s Joomla! installer unable detects any value set for session save path. To fix and solve the problem simply configure the session save path variable in the web server environment, so that session save path will be shown as Writable when Joomla! installer re-check the environment. Depending on the web hosting service you used, there are several possible solutions as listed below.

Define session.save_path directive in PHP.INI

If you have root access or control to the web host (for example, in VPS or dedicated server), edit the PHP.INI PHP configuration file in the web server to add in the environment variable. Normally the session.save_path directive is already included in the default PHP.INI, but been commented out. Add or edit the line so that it looks like below:

session.save_path = /tmp

Modify /tmp to the path to a folder that is writable by Apache web server process. If you don’t have shell access to the web host, such as in shared hosting, try asking hosting service provider to include the session save path parameter, or make the path writable.

Include session.save_path in .htaccess file

If you can’t modify PHP.INI global configuration file, or just want to make the change affect Joomla! or Mambo application only, create or edit the .htaccess file in the installation directory for Joomla! or Mambo, and add the following line (only works in Apache web server which configured to support .htaccess - most cPanel hosts do):

php_value session.save_path '/tmp'

Use Local PHP.INI in the Joomla/Mambo folder

If PHP is being run as CGI mode on the web server, or method above using .htaccess does’t work, try override the main global PHP.INI settings by using a localized PHP.INI file which located in the each and every directories for the application. However, the disadvantage is that users have to create lots of PHP.INI files as the override will be on folder by folder basis - those with local PHP.INI will be overrode, but not its parent or child sub-folders. This means that each folder that contains an executable PHP scripts must have its own PHP.INI file, such as in main root Joomla directory, /administrator/ folder and etc.

To configure the PHP override, create a PHP.INI on the folder(s) inside Joomla! directory, and add the setting in following format:

session.save_path = /tmp

Use ini_set(variable, value) to override session.save_path in Globals.php file

If nothing mentioned above you can do, then try to edit globals.php file comes with Joomla. Firstly create a writable folder, and then edit the globals.php in root Joomla! directory. Add in the following line at the top, right after <?php line:

ini_set('session.save_path','/tmp');

define( 'RG_EMULATION', 1 );

define( 'RG_EMULATION', 0 );

Add session save path parameter into Joomla’s PHP code

If it’s impossible to change PHP.INI or add .htaccess, try to create a writable directory, recommended to be a directory named ’sessions’ inside $mosConfig_absolute_path folder which can be retrieved from the configuration.php itself, then add the following line in configuration.php file of Joomla!.

session_save_path('public_html/session');

Add php_value for session.save_path in httpd.conf Apache configuration file

Create a writable directory that can be accessed by Apache service, and then edit the Apache configuration file of httpd.conf. Add the following line to the bottom of the file:

php_value session.save_path "C:\Temp\"

Note: A lot has been saying about writable folder. In some cases, depending on owner and group, you may have to set the permissions to 777 (full read, write and execute) in order for Apache to be able to write into the directory.

Above resolutions should work for both Linux, FreeBSD, Unix and Windows based web server. However in Windows, you may need to specify drive letter to the path. For example, ‘/tmp’ will be ‘C:/tmp’ in Windows. It’s also recommended to use forward slash (/) in the path to the folder instead of usual backslash (\).