Upgraded a Joomla 2.5 Component and suddenly both my Admin and Frontend were a blank screen. Ugh!
Time to debug: root > configuration.php > public $error_reporting = ‘default’;
Change the word default to maximum.
FTP: set permissions of configuration.php on server to 777; upload configuration.php from local to server. View all the pretty error messages. Change local configuration.php file’s public $error_reporting line back to default; upload to server; set server’s configuration.php permissions back to 644.
Source: How to fix a blank screen after upgrading to Joomla 3.2 – Bamboo Blog