Paypal is set as the default enrolment plugin with a site-wide cost. In the course settings, Enrolment Plugins is set to Site Default (Paypal) and Cost is left blank. The course is available to students. However, when a logged-in student clicks on the course, he gets the error message: "Could not determine course enrolment method!"

You can try it at the URL below (try "Dutch Time copy 1")