For the datetime picker, Jira does not format the am and pm.

This means that in a language like Japanese the date time picker does not work.

For example Jira willl produce

30/3月/06 12:39 PM when it needs 30/3月/06 12:39 午前

A quick workaround here is to use 24-hour time. To do this:

1. Goto WEB-INF/classes/jira-application.properties
2. Edit the date picker format lines to look like below:

   jira.date.time.picker.java.format = dd/MMM/yy HH:mm
   jira.date.time.picker.javascript.format = %e/%b/%y %H:%M
   

3. Restart Jira