After installing Drupal 7.2, after running flush, cron, and update.php, the site crashed with this error: ( ! ) Fatal error: Class 'FeedsPlugin' not found. I can revive the site by disabling the feeds module (http://www.example.com/admin/modules/list) with the list modules link.
Has anyone else had this issue when upgrading to Drupal 7.2?
An outdated registry. Drupal keeps track of which class is where on the file system in a thing that is called a registry. However, this registry isn't 100% reliable: whenever you move or update a module, the registry may become outdated. Classes may have been moved, added or deleted. The result is that Drupal no longer can find a specific class if a module requested it, even if that module contains the class in question.
Perform a registry rebuild.