Earlier today on some of my other sites I fixed this by changing timezone back and forth.
Originating timezone was Copenhagen so not a fixed UTC zone.
But on this site (multisite setup) this work around failed. I changed to Athens and back with no result – then tried to stay on Berlin but also with no result.
PHP Fatal error: Uncaught exception ‘Exception’ with message ‘DateTime::__construct() expects parameter 2 to be DateTimeZone, null given’ in /var/www/wp/wp-content/plugins/events-made-easy/ExpressiveDate.php:56\nStack trace:\n#0 /var/www/wp/wp-content/plugins/events-made-easy/ExpressiveDate.php(56): DateTime->__construct(‘2015-11-21 10:0…’, NULL)\n#1 /var/www/wp/wp-content/plugins/events-made-easy/eme_events.php(3788): ExpressiveDate->__construct(‘2015-11-21 10:0…’)\n#2 /var/www/wp/wp-content/plugins/events-made-easy/eme_events.php(460): eme_db_update_event(Array, 993)\n#3 [internal function]: eme_events_page(”)\n#4 /var/www/wp/wp-includes/plugin.php(503): call_user_func_array(’eme_events_page’, Array)\n#5 /var/www/wp/wp-admin/admin.php(236): do_action(‘toplevel_page_e…’)\n#6 {main}\n thrown in /var/www/wp/wp-content/plugins/events-made-easy/ExpressiveDate.php on line 56, referer: http://nordjylland.wp.bridge.dk/wp-admin/admin.php?page=events-manager&eme_admin_action=edit_event&event_id=993