"Cannot redeclare class themeregistry" when trying install Drupal 7

When attempting to install Drupal 7 on a server which has a few Drupal 6 installs running without a problem I got a white screen of death after selecting the profile I want to use.

Looking in the log file were quite a few lines stating:

[Wed Feb 08 10:19:55 2012] [error] [client] PHP Fatal error: require() [function.require'>function.require]: Cannot redeclare class themeregistry in /var/www/microsites/www/includes/install.inc on line 1120

The problem turned out to be an issue with an APC configuration.

In your apc.ini file change the following:




The apc.ini file on this RedHat server was located in /etc/php.d/apc.ini.