PHP Fatal Error on model

[mis-uep]

PHP error Log
PHP Fatal error: Declaration of User::findFirst($parameters = NULL) must be compatible with Phalcon\Mvc\Model::findFirst($parameters = NULL): ?Phalcon\Mvc\ModelInterface in /var/www/project_name/app/models/User.php on line 0, referer: http://ip.address/

User Model
`

/**
 *
 * @var integer
 */
public $iD;

/**
 *
 * @var string
 */
public $userName;

/**
 *
 * @var string
 */
public $password;

/**
 *
 * @var string
 */
public $userLvl;

/**
 *
 * @var string
 */
public $created_at;

/**
 *
 * @var string
 */
public $updated_at;

/**
 *
 * @var string
 */
public $status;

/**
 *
 * @var string
 */
public $emailAdd;

/**
 *
 * @var string
 */
public $adminpass;

/**
 * Initialize method for model.
 */
public function initialize()
{
    $this->setSchema("dbuep");
    $this->setSource("user");
}

/**
 * Allows to query a set of records that match the specified conditions
 *
 * @param mixed $parameters
 * @return User[]|User|\Phalcon\Mvc\Model\ResultSetInterface
 */
public static function find($parameters = null): \Phalcon\Mvc\Model\ResultsetInterface
{
    return parent::find($parameters);
}

/**
 * Allows to query the first record that match the specified conditions
 *
 * @param mixed $parameters
 * @return User|\Phalcon\Mvc\Model\ResultInterface
 */
public static function findFirst($parameters = null)
{
    return parent::findFirst($parameters);
}

`

Can you help me to solve this? thanks!

[mis-uep]

Something to do with Phalcon version issue

[mis-uep]

need to upgrade or migrate to newer version