Can't find event

When user clicks on event links in emails, they may experience a momentary glimpse of a page saying “Can't find event”. However, it load normally within a few seconds.

When you click on RSVP button in Heartbeat Desktop App it opens the “Can't find event” page and stays there but it does RSVP in the app and changes the status to "Confirmed" - critical issue, very confusing for users. Screenshot is attached.