I am installing cacti on my ubuntu server following this tutorial
When I visit, mydomain/cacti, I was redirected to mydomain/cacti/install where I chose new install and after that I got redirected to mydomain/cacti/install/index.php where all the fields are automatically set and are indicated to be ok.
However when I click finish to submit the form, a white screen is displayed and the url still remains mydomain/cacti/install/index.php**
I can't figure what I have done wrongly
My apache2 error log indicates the following
[Thu Jul 10 12:05:28.799595 2014] [:error] [pid 28811] [client 41.87.105.66:37695] PHP Fatal error: Call to undefined function session_unregister() in /usr/share/cacti/site/lib/functions.php on line 408, referer: mydomain/cacti/install/index.php
[Thu Jul 10 12:05:28.799622 2014] [:error] [pid 28811] [client 41.87.105.66:37695] PHP Stack trace:, referer: mydomain/cacti/install/index.php
[Thu Jul 10 12:05:28.799633 2014] [:error] [pid 28811] [client 41.87.105.66:37695] PHP 1. {main}() /usr/share/cacti/site/install/index.php:0, referer: mydomain/cacti/install/index.php
[Thu Jul 10 12:05:28.799643 2014] [:error] [pid 28811] [client 41.87.105.66:37695] PHP 2. kill_session_var() /usr/share/cacti/site/install/index.php:347, referer: mydomain/cacti/install/index.php