The site crashes with updating from 3.12.6 to 4.0.4. This is the message:
Fatal error: Cannot redeclare tribe_is_community_my_events_page() (previously declared in /home/xxxxxx/www/wp-content/plugins/the-events-calendar/src/functions/template-tags/query.php:67) in /home/xxxxxxx/www/wp-content/plugins/the-events-calendar-community-events/src/functions/template-tags.php on line 13
Sorry for the trouble here. The update to 4.0 is a significant one and is likely to break any customizations you might have in place from 3.12.
Do you have any snippets in your functions.php file? Or, do you have any custom templates for the calendar in your theme? You can check for custom templates by looking for a folder called tribe-events in your theme directory.