rails is looking for a template

app/controllers/staff/proposals_controller.rb

@@ -27,7 +27,7 @@ def index
            csv << [p.average_rating, p.ratings.size, p.standard_deviation, p.title, speakers[0].name, speakers[1]&.name, speakers[2]&.name, p.abstract, p.details, p.pitch, p.session_format&.name, p.track&.name, p.state]
           end
         end
-        render :csv => csv_string, :filename => "#{@event.name} #{Time.now.to_i}.csv"
+        send_data csv_string, :filename => "#{@event.name} #{Time.now.to_i}.csv"
       }
     end
   end