Why error 404 page?

1

My Client is using a very old version of SLIM. Hes has copied the SLIM code over to another Server and it doesn’t work and I can’t see why. The echo $body in this function is returning the 404 page

The page is

public function run()
{
print_r($this->middleware[0]);
set_error_handler(array(’\Slim\Slim’, ‘handleErrors’));

        //Apply final outer middleware layers
        if ($this->config('debug')) {
            //Apply pretty exceptions only in debug to avoid accidental information leakage in production
            $this->add(new \Slim\Middleware\PrettyExceptions());
        }

        //Invoke middleware and application stack
        $this->middleware[0]->call();

        //Fetch status, header, and body
        list($status, $headers, $body) = $this->response->finalize();
		print_r($this->response->finalize());

        // Serialize cookies (with optional encryption)
        \Slim\Http\Util::serializeCookies($headers, $this->response->cookies, $this->settings);

        //Send headers
        if (headers_sent() === false) {
			
            //Send status
            if (strpos(PHP_SAPI, 'cgi') === 0) {
                header(sprintf('Status: %s', \Slim\Http\Response::getMessageForCode($status)));
            } else {
				
                header(sprintf('HTTP/%s %s', $this->config('http.version'), \Slim\Http\Response::getMessageForCode($status)));
            }

            //Send headers
            foreach ($headers as $name => $value) {
                $hValues = explode("\n", $value);
                foreach ($hValues as $hVal) {
                    header("$name: $hVal", false);
                }
            }
        }

        //Send body, but only if it isn't a HEAD request
        if (!$this->request->isHead()) {
			
            echo $body;
        }
        $this->applyHook('slim.after');

        restore_error_handler();
    }

It should be going to

$app->post(’/validate_api’, function() use ($app) {

}

in index.php

Is there something we have missed? The version is 2.6.1

Thanks