Unable to open reports after iReport upgrade from 3.7 to 4.x

[uouser]

Hi,

I have upgraded my iReport software from 3.7 to 4.x version. I have quite a lot reports created in 3.7 and now I get this error when I open any report or create a blnak new report. The error is:

 

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Error loading the report template
 

Message:
    java.lang.reflect.InvocationTargetException
Level:
    SEVERE
Stack Trace:
null
    java.awt.EventQueue.invokeAndWait(EventQueue.java:998)
    javax.swing.SwingUtilities.invokeAndWait(SwingUtilities.java:1320)
    com.jaspersoft.ireport.designer.JrxmlVisualView.run(JrxmlVisualView.java:526)
    org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
    org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)
net.sf.jasperreports.engine.convert.ReportConverter. (Lnet/sf/jasperreports/engine/JRReport;Z)V
    com.jaspersoft.ireport.designer.ReportObjectScene.setJasperDesign(ReportObjectScene.java:148)
    com.jaspersoft.ireport.designer.ReportDesignerPanel.setJasperDesign(ReportDesignerPanel.java:154)
    com.jaspersoft.ireport.designer.JrxmlVisualView$3.run(JrxmlVisualView.java:530)
    java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:199)
    java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
    org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
    java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

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Any help in this regard will be highly appreciated. Thanks.