PHP Fatal error: Call to undefined function session_register()

session_register() has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 5.4.0.

Your facing this problem because of you are using PHP 5.4.0 or above

Read PHP documentation
http://www.php.net/manual/en/function.session-register.php


For solution : Remove  session_register() from you code.