I'm updating a Symfony application to use Symfony 3.3.4 and Flex 1.0.11. In my app I had this config file which maps old URLs to new URLs:

// app/config/legacy_url_map.php
<?php

return array(
    '/old-url' => '/new-url',
    // ...
);

I tried to move that file to config/routing/legacy_url_map.php but the following confusing error happened:

I guess you can't put arbitrary files inside the new config/routing/ dir ... but the error message should be improved in those cases. Thanks!