SEVERE: error handling client message [C] 03 EnterWorld
java.lang.IllegalStateException
        at net.sf.l2j.util.L2ObjectHashSet.put(L2ObjectHashSet.java:193)
        at net.sf.l2j.gameserver.model.L2Character.addKnownObject(L2Character.java:3081)
        at net.sf.l2j.gameserver.model.L2World.addVisibleObject(L2World.java:405)
        at net.sf.l2j.gameserver.model.L2Object.spawnMe(L2Object.java:323)
        at net.sf.l2j.gameserver.clientpackets.EnterWorld.runImpl(EnterWorld.java:82)
        at net.sf.l2j.gameserver.clientpackets.ClientBasePacket.run(ClientBasePacket.java:56)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)
        at java.util.concurrent.FutureTask.run(FutureTask.java:123)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:6
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:168)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
        at java.lang.Thread.run(Thread.java:595)