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 SlimContainer(); //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
$app = new SlimApp($c);

//... Your code

In this example, we define a new notFoundHandler factory that returns a callable. The returned callable accepts two arguments:

1. A PsrHttpMessageServerRequestInterface instance
2. A PsrHttpMessageResponseInterface instance

The callable MUST return an appropriate PsrHttpMessageResponseInterface instance.