[SOLVED] I've defined a bundle Controller and Routing, but I get "Error: the controller does neither exist as service nor as class"

I've defined a bundle Controller and Routing, but I get "Error: the controller does neither exist as service nor as class"

I have created a controller class under a module directory in Symfony 4. My bundle's routing file references it. My root's routing file includes the bundle's routing file.

However I get an error 500, "Error: the controller does neither exist as service nor as class".

Why?

root/src/MyBundle/Resources/config/routing.YML

route_name:
  path: /test3
  controller: MyBundle\Controller\ExportCsvController::exportProductInCsv
  options:
    expose: true

root/config/routes/my_custom_routes.YML

route_name:
      resource: "@MyBundle/Resources/config/routing.yml"
      prefix:   /

root/src/MyBundle/Controller/ExportCsvController.PHP

<?php
namespace MyBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;

class ExportCsvController extends Controller
{
    public function exportProductInCsv(): Response
    {
        return new Response(
            '<html><body>test</body></html>'
        );
    }
}

Solution

It was a problem of cache (Symfony cache). Solved with this command: php bin/console cache:clear --env=prod. Now the content of the file root/src/MyBundle/Resources/config/routing.YML is correctly taken into account :).