OK, i can't check directly on production server... But i've tried a test. I have made a small simple report with some of DateTime functions which are inside jasperreports-functions libs... And it's pretty weird... NOW(), DAY(), SECOND(), DATEVALUE() are OK and functionnal, but DAYS(), YEARS(), MONTHS() give me the error mentionned here... And these methods are using another method from joda-time lib, so it seems joda-time is the missing libray on theserver