**Symfony version(s) affected**: 4.1 (Without Flex) **Description** <!-- A clear and concise description of the problem. --> After update from 4.0.11 to 4.1 error ```The configuration tree has no root node.``` is presented. Issue is mentioned in comment https://symfony.com/blog/symfony-4-1-0-released#comment-22501 **How to reproduce** Update non flex symfony app to 4.1 with bundle without root node. <!-- Code and/or config needed to reproduce the problem. If it's a complex bug, create a "bug reproducer" as explained in: https://symfony.com/doc/current/contributing/code/reproducer.html --> **Additional context** <!-- Optional: any other context about the problem: log messages, screenshots, etc. --> 