Error after signup

[wcousin]

I'm getting an error after I install signup-download as you are instructed in the tutorial. Here is the error:

undefined method async' for # The issues is in app/models/users.rb on line 15 that reads:MailingListSignupJob.perform_later(self)`

The tutorial says

After submitting the form, you’ll see an acknowledgment message and a button which allows you to download a PDF file.

But, instead I'm getting this error.