php update to 7.4 makes wp pages uneditable

I upgraded the php to 7.4 to enable Calendarizeit to work properly but in so doing any standard pages became inaccessible to edit. Both the classic mode and backend editor mode of the visual composer were disabled. I need both pages and Calendarize it to work properly. Is there a compromise. Suggestions would be appreciated and questions will be answered to the best of my ability.