Log in as an administrator. Click on the date on the Calendar block. Click on 'Manage Subscriptions'. Fill in a name for the Calendar Select "Import from" = "Calendar URL" and leave Calendar url blank. You should see "Invalid url" error and no new subscription entry should be added. Enter invalid url and you should see error click continue and you should go back to manage subscription page. Enter valid calendar url ( https://www.google.com/calendar/ical/en.australian%23holiday%40group.v.calendar.google.com/public/basic.ics ) and you should see new subscription entry. Now try again with "Import from" = "Calendar FILE" Don't attach file and you should see "Either a URL or a file is required to import a calendar." error and no new subscription should be added. Attach a file and you should see new subscription.