In the new version 3.10.205 there is a bug in the event editor, when selecting "no end date" in the timing tab.
The SQL Statement is displayed and executed as follows:
...
ON SCHEDULE EVERY '1' MONTH
STARTS '2009-01-01 00:00:00'
ENDS CURRENT_TIMESTAMP
ON COMPLETION PRESERVE
DO
...
This cause an error "ENDS is either invalid or before STARTS"
I think the ends clause must be removed in the SQL when selecting no end date.