Application.js can't find @rails

Question

I'm updating a fairly old project to rails 6, and adapt to current "rails ways". And I've just installed webpacker, but I've run into problem I can't seem to find a way to solve.

When running the project, I get this error: Uncaught Error: Cannot find module '@rails/ujs'

I've tried to reinstall rails-ujs through yarn, but to no effect.

Also I've tried to comment the line require("@rails/ujs").start() from my app/javascript/packs/application.js , and yet I got another error: Uncaught Error: Cannot find module '@rails/activestorage' .

Which leads me to believe that its the global @rails that is not being recognized, however I have no idea where is it set or how to do so.

My questions are: Can I set @rails myself?

Is there a way to re-generate it?

or

Is there another configuration I should fix?

Answer 1

It's not @rails which is missing, it's the ujs (and active storage) JavaScript packages which are missing.

Run yarn install To install them.