A few days ago I noted a quick but very usefull tip on how to handle the situation when Front Controller is unable to dispatch the request, i.e. how to display 404 error page instead of Zend_Controller_Dispatcher_Exception with message "Invalid controller specified". And it looks like the common solution for this is to create a front controller plugin. The plugin detects whether the request is dispatchable and changes module/controller/action to appropriate action that will handle the request.

His solution uses a NoRoute controller to check and see if there is a valid controller for the requested action. If not, it routes them to a custom controller with a nicer error message. For those that want a bit more low level type of solution, he also includes how to modify the framework itself to perform the same action.

Early versions of the Zend Framework had a noRoute action that was called when the correct action couldn't be found. This was a way to deal with some page not found errors. At some point it was dropped - I don't know when or why because I only started using the Zend Framework recently. It's still possible to handle non-existent actions using the __call() method of the controller class. But there's no obvious way to deal with all page not found errors in one place, including instances where the controller doesn't exist.

The framework makes it easy to create actions link to controllers, but there's still a problem when a requested action isn't there. His plugin has a solution to that - it is fired off when the action requested doesn't exist and automatically reroutes it to the "noroute" controller to be handled.