If, after trying to install new modules, you encounter a blank screen when visiting Administer-->Site Building-->Modules, you probably need to increase your PHP memory.

Verify the Memory Problem

First, verify that your PHP memory limit is the cause of the problem. Locate your PHP error log file.

Problem

You receive a error message at the bottom of the screen reading The mysqli error was: Unable to use the MySQLi database because the MySQLi extension for PHP is not installed. Check your <code>php.ini</code> to see how you can enable it.

Scenario

You followed all of the instructions to manually transfer your test machine site via FTP to the web. You visit your site and encounter a Drupal screen indicating the site is off-line.