Today I wanted to install Drupal 7 manually from the root of a subdomain I set-up and was confronted with a blank page. I checked many different things like is PDO enabled? Do I have the minimum version of Php installed? Then I delved into the Apache2 logs at /var/log/apache2 and noticed this error:
[Thu Jun 16 10:15:41 2011] [error] [client 10.20.201.98] PHP Fatal error: require_once(): Failed opening required '/var/www/dev/includes/bootstrap.inc' (include_path='.:/usr/share/php:/usr/share/$
As it turned out I hadn’t used CHMOD to modify permissions of the Drupal Core files when I’d copied them across Chmodding them to 555 solved this issue.