In 4.0.5 of Events Calendar Pro, the class Tribe__Notice is called. It looks like the valid class is really the plural Tribe__Notices, which is included The Events Calendar.
This issue was previously brought to attention in https://theeventscalendar.com/support/forums/topic/php-fatal-error-class-tribe__notice-not-found/, but it appears it has not been fixed in the latest release of Events Calendar Pro.
I believe all that’s needed is to change uses of Tribe__Notice to Tribe__Notices. I would submit a patch if a public repo was available. 😉
I have not troubleshot further by deactivating other plugins, etc.. as the problem seems to be very straight forward. I’ll patch in production, but would appreciate an update in the next release.
Thanks!
