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Posted to user@openmeetings.apache.org by Rodolfo Gonzalez <ro...@gmail.com> on 2020/03/26 15:21:42 UTC

[Wicket-AsyncPageStore-PageSavingThread] org.apache.wicket.serialize.java.JavaSerializer - error writing object

Third message of the day. I'm getting paranoic :D

OM 4.0.10, openjdk 11, ubuntu 18.04

I'm getting this too, but I don't know neither the effect nor the cause:

[ERROR] [Wicket-AsyncPageStore-PageSavingThread]
org.apache.wicket.serialize.java.JavaSerializer - error writing object
[Page class = org.apache.openmeetings.web.pages.HashPage, id = 0, render
count = 1]: null
java.util.ConcurrentModificationException: null
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:900)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at
org.apache.wicket.serialize.java.JavaSerializer$SerializationCheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:368)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345)
        at
org.apache.wicket.serialize.java.JavaSerializer.serialize(JavaSerializer.java:82)
        at
org.apache.wicket.pageStore.AbstractPageStore.serializePage(AbstractPageStore.java:133)
        at
org.apache.wicket.pageStore.DefaultPageStore.createSerializedPage(DefaultPageStore.java:281)
        at
org.apache.wicket.pageStore.DefaultPageStore.storePage(DefaultPageStore.java:61)
        at
org.apache.wicket.pageStore.AsynchronousPageStore$PageSavingRunnable.run(AsynchronousPageStore.java:208)
        at java.base/java.lang.Thread.run(Thread.java:834)
[ERROR] [Wicket-AsyncPageStore-PageSavingThread]
org.apache.wicket.serialize.java.JavaSerializer - Error serializing object
class org.apache.openmeetings.web.pages.HashPage [object=[Page class =
org.apache.openmeetings.web.pages.HashPage, id = 0, render count = 1]]
org.apache.wicket.WicketRuntimeException:
java.util.ConcurrentModificationException
        at
org.apache.wicket.serialize.java.JavaSerializer$SerializationCheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:402)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345)
        at
org.apache.wicket.serialize.java.JavaSerializer.serialize(JavaSerializer.java:82)
        at
org.apache.wicket.pageStore.AbstractPageStore.serializePage(AbstractPageStore.java:133)
        at
org.apache.wicket.pageStore.DefaultPageStore.createSerializedPage(DefaultPageStore.java:281)
        at
org.apache.wicket.pageStore.DefaultPageStore.storePage(DefaultPageStore.java:61)
        at
org.apache.wicket.pageStore.AsynchronousPageStore$PageSavingRunnable.run(AsynchronousPageStore.java:208)
        at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.util.ConcurrentModificationException: null
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:900)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
        at
java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
Source)
        at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at
java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
        at
java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
        at
java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
        at
java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
        at
java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
        at
org.apache.wicket.serialize.java.JavaSerializer$SerializationCheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:368)

Thanks.

Re: [Wicket-AsyncPageStore-PageSavingThread] org.apache.wicket.serialize.java.JavaSerializer - error writing object

Posted by Maxim Solodovnik <so...@gmail.com>.

Saw zero errors like this on demo
I guess you can ignore it

On Thu, 26 Mar 2020 at 22:21, Rodolfo Gonzalez <ro...@gmail.com>
wrote:

> Third message of the day. I'm getting paranoic :D
>
> OM 4.0.10, openjdk 11, ubuntu 18.04
>
> I'm getting this too, but I don't know neither the effect nor the cause:
>
> [ERROR] [Wicket-AsyncPageStore-PageSavingThread]
> org.apache.wicket.serialize.java.JavaSerializer - error writing object
> [Page class = org.apache.openmeetings.web.pages.HashPage, id = 0, render
> count = 1]: null
> java.util.ConcurrentModificationException: null
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:900)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at
> org.apache.wicket.serialize.java.JavaSerializer$SerializationCheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:368)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345)
>         at
> org.apache.wicket.serialize.java.JavaSerializer.serialize(JavaSerializer.java:82)
>         at
> org.apache.wicket.pageStore.AbstractPageStore.serializePage(AbstractPageStore.java:133)
>         at
> org.apache.wicket.pageStore.DefaultPageStore.createSerializedPage(DefaultPageStore.java:281)
>         at
> org.apache.wicket.pageStore.DefaultPageStore.storePage(DefaultPageStore.java:61)
>         at
> org.apache.wicket.pageStore.AsynchronousPageStore$PageSavingRunnable.run(AsynchronousPageStore.java:208)
>         at java.base/java.lang.Thread.run(Thread.java:834)
> [ERROR] [Wicket-AsyncPageStore-PageSavingThread]
> org.apache.wicket.serialize.java.JavaSerializer - Error serializing object
> class org.apache.openmeetings.web.pages.HashPage [object=[Page class =
> org.apache.openmeetings.web.pages.HashPage, id = 0, render count = 1]]
> org.apache.wicket.WicketRuntimeException:
> java.util.ConcurrentModificationException
>         at
> org.apache.wicket.serialize.java.JavaSerializer$SerializationCheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:402)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:345)
>         at
> org.apache.wicket.serialize.java.JavaSerializer.serialize(JavaSerializer.java:82)
>         at
> org.apache.wicket.pageStore.AbstractPageStore.serializePage(AbstractPageStore.java:133)
>         at
> org.apache.wicket.pageStore.DefaultPageStore.createSerializedPage(DefaultPageStore.java:281)
>         at
> org.apache.wicket.pageStore.DefaultPageStore.storePage(DefaultPageStore.java:61)
>         at
> org.apache.wicket.pageStore.AsynchronousPageStore$PageSavingRunnable.run(AsynchronousPageStore.java:208)
>         at java.base/java.lang.Thread.run(Thread.java:834)
> Caused by: java.util.ConcurrentModificationException: null
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:900)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at java.base/java.util.ArrayList.writeObject(ArrayList.java:896)
>         at
> java.base/jdk.internal.reflect.GeneratedMethodAccessor185.invoke(Unknown
> Source)
>         at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
>         at
> java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
>         at
> java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
>         at
> java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
>         at
> java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
>         at
> java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
>         at
> org.apache.wicket.serialize.java.JavaSerializer$SerializationCheckerObjectOutputStream.writeObjectOverride(JavaSerializer.java:368)
>
> Thanks.
>


-- 
WBR
Maxim aka solomax