[Anthill-pro] exception in log

[Byron Appelt]

I have many of the following excceptions in my tomcat logs, what how
can I correct this?

SEVERE: Exception loading sessions from persistent storage
java.io.WriteAbortedException: writing aborted;
java.io.NotSerializableException: com.urbancode.anthill2.ui.tree.Node
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1308)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1917)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1841)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1718)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1304)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:349)
        at org.apache.catalina.session.StandardSession.readObject(StandardSession.java:1386)
        at org.apache.catalina.session.StandardSession.readObjectData(StandardSession.java:921)
        at org.apache.catalina.session.StandardManager.doLoad(StandardManager.java:393)
        at org.apache.catalina.session.StandardManager.load(StandardManager.java:320)
        at org.apache.catalina.session.StandardManager.start(StandardManager.java:636)
        at org.apache.catalina.core.ContainerBase.setManager(ContainerBase.java:431)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4131)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
        at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:809)
        at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:698)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:472)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1122)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:310)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1021)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1013)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
        at org.apache.catalina.core.StandardService.start(StandardService.java:450)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:709)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:551)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
Caused by: java.io.NotSerializableException: com.urbancode.anthill2.ui.tree.Node
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1081)
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1375)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1347)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1290)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1079)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:302)
        at org.apache.catalina.session.StandardSession.writeObject(StandardSession.java:1462)
        at org.apache.catalina.session.StandardSession.writeObjectData(StandardSession.java:938)
        at org.apache.catalina.session.StandardManager.doUnload(StandardManager.java:516)
        at org.apache.catalina.session.StandardManager.unload(StandardManager.java:462)
        at org.apache.catalina.session.StandardManager.stop(StandardManager.java:666)
        at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4345)
        at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:892)
        at org.apache.catalina.startup.HostConfig.undeployApps(HostConfig.java:1164)
        at org.apache.catalina.startup.HostConfig.stop(HostConfig.java:1135)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:312)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
        at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1054)
        at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1066)
        at org.apache.catalina.core.StandardEngine.stop(StandardEngine.java:447)
        at org.apache.catalina.core.StandardService.stop(StandardService.java:512)
        at org.apache.catalina.core.StandardServer.stop(StandardServer.java:743)
        at org.apache.catalina.startup.Catalina.stop(Catalina.java:601)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:576)
        ... 6 more