I put a null-test instead of just commenting out. With this line no longer erroring, all my other calendar problems cleared up as well.
//$end_iso = $end->toIso8601String();
$end_iso = ! is_null( $end ) ? $end->toIso8601String() : null;
Same here. WordPress 4.6.1, just upgraded SimpleCalendar to 3.1.5, and getting the same error message:
[26-Sep-2016 14:52:15 UTC] PHP Fatal error: Call to a member function toIso8601String() on a non-object in /home/my-site-name/public_html/wp-content/plugins/google-calendar-events/includes/events/event-builder.php on line 688
My calendars are broken – next/prev buttons not working, label messed up. I’ll try commenting out this line as you did and see if it helps, but of course it’s not a great resolution.
