java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
        at java.util.HashMap$ValueIterator.next(Unknown Source)
        at net.sf.l2j.gameserver.model.L2Attackable.calculateRewards(L2Attackable.java:388)
        at net.sf.l2j.gameserver.model.L2Attackable.doDie(L2Attackable.java:329)
        at net.sf.l2j.gameserver.model.L2Character.reduceCurrentHp(L2Character.java:2619)
        at net.sf.l2j.gameserver.model.L2Attackable.reduceCurrentHp(L2Attackable.java:308)
        at net.sf.l2j.gameserver.model.L2Attackable.reduceCurrentHp(L2Attackable.java:277)
        at net.sf.l2j.gameserver.model.L2Character.onHitTimer(L2Character.java:3852)
        at net.sf.l2j.gameserver.model.L2PcInstance.onHitTimer(L2PcInstance.java:1740)
        at net.sf.l2j.gameserver.model.L2Character$HitTask.run(L2Character.java:239)
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
        at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(Unknown Source)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)