Phalcon\Mvc\View\Engine\Volt\Exception: Volt directory can't be written

<?php 
 
class Bootstrap extends \Phalcon\Mvc\Application {
    private $modules;
    private $default_module = 'backend';
        
    public function __construct($default_module) {
        $this->modules = array(
            'core' => array(
                'className' => 'App\Core\Module',
                'path' => __DIR__ . '/Core/Module.php'
            ),
            'api' => array(
                'className' => 'App\Api\Module',
                'path' => __DIR__ . '/Api/Module.php'
            ),
            'backend' => array(
                'className' => 'App\Backend\Module',
                'path' => __DIR__ . '/Backend/Module.php'
            ),
        );
        
        $this->default_module = $default_module;
    }
    
    private function _registerServices() {
        $default_module = $this->default_module;
        $di = new \Phalcon\DI\FactoryDefault();
        $config = require __DIR__ . '/../config/config.php';
        $modules = $this->modules;
        
 
        include_once __DIR__ . '/../vendor/autoload.php';
        include_once __DIR__ . '/../config/loader.php';
        include_once __DIR__ . '/../config/services.php';
        include_once __DIR__ . '/../config/routing.php';
        
        $this->setDI($di);
    }
    
    public function init() {
        $debug = new \Phalcon\Debug();
        $debug->listen();
        
        $this->_registerServices();
        $this->registerModules($this->modules);
        
        echo $this->handle()->getContent();
    }
}

<?php
 
define('APP_PATH', realpath(dirname(__DIR__)));
 
//header('Content-type', 'text/html; charset=utf-8');
mb_internal_encoding('UTF-8');
 
require_once __DIR__ . '/../vendor/autoload.php';
require_once __DIR__ . '/../modules/Bootstrap.php';
 
$app = new Bootstrap('backend');
$app->init();