FOSUserBundle & Symfony 3.4 : login page show 404 page in production mode

Question

I'm using FOSUserBundle v2.1.2 with Symfony 3.4 and every thing is working fine in dev mode but in prod, web/app.php/login shows 404 page. I've tried to solve it by doing the following methods in vain:

• bin/console cache:clear --env=prod
• Remove var/cache : rm -r var/cache
• set in $kernel = new AppKernel('prod', false); in web/app.php.
• composer update friendsofsymfony/user-bundle : successfully updated.

Notice: both /web/login and /web/app.php/login are not working