If you get this error:
Fatal error: session_start(): Failed to initialize storage module:
The solution is changing your current php.ini settings for session.save_handler user to session.save_handler files.

Edit your php.ini file from:

[Session]
; Handler used to store/retrieve data.
session.save_handler = user

to

[Session]
; Handler used to store/retrieve data.
session.save_handler = files

If you do not have access to the php.ini file, you may try an alternate .htaccess rewrite method. Edit your .htaccess and place the following lines:

RewriteEngine On
php_value session.save_handler files