Open the File Manager
Right click the php.ini file inside public_html.
Select Code Edit
Around line 824 is something which looks like this:
;session.save_path = /tmp
Remove the semicolon ';' in the front so it looks like this:
session.save_path = /tmp
Finally, make the path go to the temp folder on your account
session.save_path = /home/username/tmp
where username is your cPanel username listed inside of cPanel.
Save the Changes
If the error persists, one of two things can be done:
Place a copy of the modified php.ini file into the "administrator" or other appropriate folder
Inside cPanel, select the PHP Config icon, enable PHP 5 (FastCGI) and Save Changes
Keywords: session.save_path session save path unwritable error problem message