The MVC components in Zend Framework utilize a Front Controller, which means that all requests to a given site will go through a single entry point. As a result, all exceptions bubble up to the Front Controller eventually, allowing the developer to handle them in a single location.
However, exception messages and backtrace information often contain
sensitive system information, such as SQL statements, file
locations, and more. To help protect your site, by default
Zend_Controller_Front catches all exceptions and
registers them with the response object; in turn, by default, the
response object does not display exception messages.