When I edit or release a version in JIRA, I get an error Please enter the date in the following format: d/MMM/yy unless I select the data again using the calendar widget. Strange this is that the date populates in MMM/dd/yy format however to enter it you must enter it in the d/MMM/YY format. I don't know if this is due to system settings.
JIRA version 4.4.4