Fatal error: Uncaught Error: Class ‘BBP_BuddyPress_Activity’ not found

Investigation A client of mine wanted to disable the activity stream, went to Dashboard > Settings >¬†BuddyPress¬†> Components > Activity Streams, and Unticked the option. After they hit save, the site displayed the error ‘There has been a critical error on this website’ and the entire website (including admin dashboard) was unreachable/unusable (only returning this …