Phalcon\Mvc\Dispatcher\Exception: Backend\Controllers\SustentabilidadController handler class cannot be loaded

<?php
use Phalcon\Loader;
use Phalcon\Di\FactoryDefault;
use Phalcon\Mvc\View;
use Phalcon\Mvc\Application;
use Phalcon\Url;
use Phalcon\Mvc\Dispatcher;
use Phalcon\Session\Manager;
use Phalcon\Session\Adapter\Stream as SessionStream;
use Phalcon\Logger\Adapter\Stream as LoggerStream;
use Phalcon\Logger;
use Phalcon\Db\Adapter\PdoFactory;
use Phalcon\Mvc\Model\MetaData\Stream as Metadata;
use Phalcon\Mvc\Model\MetaData\Strategy\Annotations;
use Phalcon\Storage\SerializerFactory;
use Phalcon\Cache\Adapter\Stream as CacheStream;
use Phalcon\Crypt;
use Phalcon\Debug;
 
// Load defines
include_once 'define.php';
require_once '../vendor/autoload.php';
 
ini_set("error_log", DATA_PATH."/errors.log");
// register loader for paths
$loader = new Loader();
$loader->registerNamespaces([
    "Backend\Controllers" => APP_PATH."/controllers/",
    "Backend\Models" => APP_PATH."/models/",
    "Backend\Forms" => APP_PATH."/forms/"
]);
$loader->register();
 
// Dependencies
$di = new FactoryDefault();
 
// dispatcher
$di->setShared("dispatcher", function () {
    $dispatcher = new Dispatcher();
    $dispatcher->setDefaultNamespace("Backend\Controllers");
    return $dispatcher;
});
// view
$di->setShared("view", function () {
    $view = new View();
    $view->setViewsDir(APP_PATH."/views/")
         ->setPartialsDir("partials/");
    return $view;
});
// url
$di->setShared("url", function () {
    $url = new Url();
    $url->setBaseUri("/");
    return $url;
});
// db
$di->setShared("db", function () {
    $factory = new PdoFactory();
    
    return $factory->newInstance("mysql", [
        "host" => "localhost",
        "username" => "ecoparkcenter",
        "password" => "sP4fP9oL8vM7pL7x",
        "dbname" => "ecoparkcenter"
    ]);
});
// session
$di->setShared("session", function () {
    $session = new Manager();
    $files = new SessionStream([
        "savePath" => DATA_PATH."/sessions/"
    ]);
    $session->setAdapter($files);
    $session->start();
    return $session;
});
// logger
$di->setShared("logger", function () {
    $stream = new LoggerStream(DATA_PATH."/app.log");
    $logger = new Logger("messages", ["main" => $stream]);
    
    return $logger;
});
// metadata
$di->setShared("modelsMetadata", function () use ($di) {
    $metadata = new Metadata(["metaDataDir" => DATA_PATH."/cache/"]);
    $metadata->setStrategy(new Annotations());
    return $metadata;
});
// models cache
$di->setShared("modelsCache", function () {
    $serializerFactory = new SerializerFactory();
    $options = [
        "defaultSerializer" => "php",
        "lifetime" => 7200,
        "storageDir" => DATA_PATH."/cache"
    ];
    return new CacheStream($serializerFactory, $options);
});
// crypt
$di->setShared("crypt", function () {
    $crypt = new Crypt();
    $crypt->setKey('|&-(GL(G"h4bqO4Ry"?0-#R[?l9.uCT_');
    return $crypt;
});
    
// Load application mvc
$application = new Application($di);
 
(new Debug())->listen();
$application->handle($_SERVER["REQUEST_URI"])
            ->send();