How to debug issues with zeitwerk and Rails

In case you have trouble with the zeitwerk autoloader, you can check out the documentation Autoloading and Reloading Constants Archive and Classic to Zeitwerk HOWTO Archive for some debugging hints.

For myself it was useful to print the registered constants and the file references during the boot. Therefore you need to add Rails.autoloaders.log at the end of your config/application.rb file. You could also run bin/rails zeitwerk:check for a more generic check.