Michael Catanzaro created an issue #548:
Hi, it seems our ical release schedule at https://www.gnome.org/start/unstable/schedule.ics has broken somehow. That is supposed to redirect to https://static.gnome.org/calendars/schedule-unstable.ics. I see the redirect still exists in the server config here, but it seems to not be working for whatever reason, dunno why.
There is no amazing reason to have the redirect, so I changed our instructions for subscribing to the calendar to point directly to the real location. It would be good to fix the redirect for anyone who has already subscribed to it if possible, but not super important.