# 404 Not Found Handler If your Slim Framework application does not have a route that matches the current HTTP request URI, the application invokes its Not Found handler and returns a?`HTTP/1.1 404 Not Found`?response to the HTTP client. ## Default Not Found handler Each Slim Framework application has a default Not Found handler. This handler sets the Response status to?`404`, it sets the content type to?`text/html`, and it writes a simple explanation to the Response body. ## Custom Not Found handler A Slim Framework application’s Not Found handler is a Pimple service. You can substitute your own Not Found handler by defining a custom Pimple factory method with the application container. ~~~ $c = new \Slim\Container(); //Create Your container //Override the default Not Found Handler $c['notFoundHandler'] = function ($c) { return function ($request, $response) use ($c) { return $c['response'] ->withStatus(404) ->withHeader('Content-Type', 'text/html') ->write('Page not found'); }; }; //Create Slim $app = new \Slim\App($c); //... Your code ~~~ In this example, we define a new?`notFoundHandler`?factory that returns a callable. The returned callable accepts two arguments: 1. A?`\Psr\Http\Message\ServerRequestInterface`?instance 2. A?`\Psr\Http\Message\ResponseInterface`?instance The callable?MUST?return an appropriate?`\Psr\Http\Message\ResponseInterface`?instance.