Fixes not being able to find the 404 page file

app/controllers/application_controller.rb

@@ -20,7 +20,7 @@ class ApplicationController < ActionController::Base
   end
 
   def not_found
-    render file: 'app/views/errors/404', status: :not_found, layout: false
+    render file: 'app/views/errors/404.html', status: :not_found, layout: false
   end
 
   def after_sign_in_path_for(_resource)