Error/Exception Handling

Kohana provides both an exception handler and an error handler that transforms errors into exceptions using PHP's ErrorException class. Many details of the error and the internal state of the application is displayed by the handler:

1. Exception class
2. Error level
3. Error message
4. Source of the error, with the error line highlighted
5. A debug backtrace of the execution flow
6. Included files, loaded extensions, and global variables

Example

Click any of the links to toggle the display of additional information:

Disabling Error/Exception Handling

If you do not want to use the internal error handling, you can disable it (highly discouraged) when calling Kohana::init:

Kohana::init(array('errors' => FALSE));

Error Reporting

By default, Kohana displays all errors, including strict mode warnings. This is set using error_reporting:

error_reporting(E_ALL | E_STRICT);

When you application is live and in production, a more conservative setting is recommended, such as ignoring notices:

error_reporting(E_ALL & ~E_NOTICE);

If you get a white screen when an error is triggered, your host probably has disabled displaying errors. You can turn it on again by adding this line just after your error_reporting call:

ini_set('display_errors', TRUE);

Errors should always be displayed, even in production, because it allows you to use exception and error handling to serve a nice error page rather than a blank white screen when an error happens.

HTTP Exception Handling

Kohana comes with a robust system for handing http errors. It includes exception classes for each http status code. To trigger a 404 in your application (the most common scenario):

throw new HTTP_Exception_404('File not found!');

There is no default method to handle these errors in Kohana. It's recommended that you setup an exception handler (and register it) to handle these kinds of errors. Here's a simple example that would go in /application/classes/foobar/exception/handler.php:

class Foobar_Exception_Handler
{
    public static function handle(Exception $e)
    {
        switch (get_class($e))
        {
            case 'Http_Exception_404':
                $response = new Response;
                $response->status(404);
                $view = new View('error_404');
                $view->message = $e->getMessage();
                $view->title = 'File Not Found';
                echo $response->body($view)->send_headers()->body();
                return TRUE;
                break;
            default:
                return Kohana_Exception::handler($e);
                break;
        }
    }
}

And put something like this in your bootstrap to register the handler.

set_exception_handler(array('Foobar_Exception_Handler', 'handle'));

Note: Be sure to place set_exception_handler() after Kohana::init() in your bootstrap, or it won't work.

If you receive Fatal error: Exception thrown without a stack frame in Unknown on line 0, it means there was an error within your exception handler. If using the example above, be sure 404.php exists under /application/views/error/.