Hi Lucian, Here is the stack trace: net.sf.jasperreports.engine.JRRuntimeException: java.lang.StackOverflowErrorat net.sf.jasperreports.engine.fill.JRFillSubreport.prepare(JRFillSubreport.java:886)at net.sf.jasperreports.engine.fill.JRFillElementContainer.prepareElements(JRFillElementContainer.java:352)at net.sf.jasperreports.engine.fill.JRFillBand.fill(JRFillBand.java:421)at net.sf.jasperreports.engine.fill.JRFillBand.fill(JRFillBand.java:396)at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(JRVerticalFiller.java:2060)at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(JRVerticalFiller.java:752)at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:259)at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:119)at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:558)at net.sf.jasperreports.engine.fill.JRFiller.fill(JRFiller.java:164)at net.sf.jasperreports.engine.JasperFillManager.fill(JasperFillManager.java:474)at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:875)...................a few references to our custom code here..................... at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)at java.lang.Thread.run(Thread.java:745)Caused by: java.lang.StackOverflowErrorat java.util.HashMap$EntryIterator.<init>(HashMap.java:1469)at java.util.HashMap$EntrySet.iterator(HashMap.java:1013)at java.util.AbstractMap.hashCode(AbstractMap.java:528) I looked through similar postings and they indicated that this may potentially be caused by the Javaflow library. I have both a regular jasperreports library and a javaflow library in the class path. I tried to exclude javaflow libraries from the build but wasn't able to as there is still some dependency there. Instead, i added a jasperreports.properties files that hasnet.sf.jasperreports.subreport.runner.factory=net.sf.jasperreports.engine.fill.ThreadPoolSubreportRunnerFactory.Before, the default.jasperreports.properties was used and I guess the one that comes from javaflow took precedenceso the original property was net.sf.jasperreports.subreport.runner.factory=net.sf.jasperreports.engine.fill.JRContinuationSubreportRunnerFactory.Now, with ThreadPoolSubreportRunnerFactory property, i don't get the stackOverflowError anymore.That being said, I'm not sure what I did was correct and the problem won't resurface again later.Do you think this should solve the problem? Do we know why Javaflow may cause problems? Should I expect the error to re-appear? Thanks for your help!NK