2015-05-21 11:52:47,238 [AWT-EventQueue-0] INFO  Opened: data/nqueens/unsolved/4queens.xml
2015-05-21 11:52:48,827 [SwingWorker-pool-3-thread-1] INFO  Solving started: time spent (10), best score (uninitialized/0), environment mode (FULL_ASSERT), random (JDK with seed 0).
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Solving failed.
	at org.optaplanner.examples.common.swingui.SolverAndPersistenceFrame$SolveWorker.done(SolverAndPersistenceFrame.java:297)
	at javax.swing.SwingWorker$5.run(SwingWorker.java:737)
	at javax.swing.SwingWorker$DoSubmitAccumulativeRunnable.run(SwingWorker.java:832)
	at sun.swing.AccumulativeRunnable.run(AccumulativeRunnable.java:112)
	at javax.swing.SwingWorker$DoSubmitAccumulativeRunnable.actionPerformed(SwingWorker.java:842)
	at javax.swing.Timer.fireActionPerformed(Timer.java:312)
	at javax.swing.Timer$DoPostEvent.run(Timer.java:244)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:312)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:745)
	at java.awt.EventQueue.access$300(EventQueue.java:103)
	at java.awt.EventQueue$3.run(EventQueue.java:706)
	at java.awt.EventQueue$3.run(EventQueue.java:704)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:715)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Caused by: java.lang.NullPointerException
	at org.optaplanner.core.impl.score.director.AbstractScoreDirector.assertWorkingScoreFromScratch(AbstractScoreDirector.java:332)
	at org.optaplanner.core.impl.solver.scope.DefaultSolverScope.assertWorkingScoreFromScratch(DefaultSolverScope.java:118)
	at org.optaplanner.core.impl.phase.scope.AbstractPhaseScope.assertWorkingScoreFromScratch(AbstractPhaseScope.java:131)
	at org.optaplanner.core.impl.exhaustivesearch.DefaultExhaustiveSearchPhase.restoreWorkingSolution(DefaultExhaustiveSearchPhase.java:214)
	at org.optaplanner.core.impl.exhaustivesearch.DefaultExhaustiveSearchPhase.solve(DefaultExhaustiveSearchPhase.java:103)
	at org.optaplanner.core.impl.solver.DefaultSolver.runPhases(DefaultSolver.java:213)
	at org.optaplanner.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:176)
	at org.optaplanner.examples.common.business.SolutionBusiness.solve(SolutionBusiness.java:302)
	at org.optaplanner.examples.common.swingui.SolverAndPersistenceFrame$SolveWorker.doInBackground(SolverAndPersistenceFrame.java:286)
	at org.optaplanner.examples.common.swingui.SolverAndPersistenceFrame$SolveWorker.doInBackground(SolverAndPersistenceFrame.java:276)
	at javax.swing.SwingWorker$1.call(SwingWorker.java:296)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at javax.swing.SwingWorker.run(SwingWorker.java:335)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)