Error when trying to add custom collections to multiple blogs


I’m getting this error when trying to add custom collections to a blog I have going:

Path coffee/roasts/dark.html proxies to unknown file roast.html:["coffee/articles/2021-01-01-example-article.html", "coffee/articles/2021-08-06-test-2.html", "coffee/roast.html", "coffee/index.html", "images/my-face.png", "images/.keep", "index.html", "javascripts/site.js", "stylesheets/site.css", "coffee/tags/example.html", "coffee/tags/nonono.html", "coffee/2021.html", "coffee/2021/08.html", "coffee/2021/08/06.html", "coffee/2021/08/01.html", "coffee/roasts/dark.html", "coffee/roasts/medium.html"] (RuntimeError)

After trying to follow the documentation, this is what my config.rb looks like:

activate :blog do |blog| = "coffee"
  blog.prefix = "coffee"
  blog.sources = "articles/{year}-{month}-{date}-{title}.html"
  blog.layout = "coffee"
  blog.tag_template = "coffee/tag.html"
  blog.calendar_template = "coffee/calendar.html"
  blog.custom_collections = {
    roast: {
      link: "coffee/roasts/{roast}.html",
      template: "coffee/roast.html"

This is my directory layout:


From what I’ve checked so far, everything seems to be in the right place. This video also seems to be doing the same thing.

I don’t know what I’m missing at this point, and so any help would be great.