We upraded to Jenkins 1.491 and updated the plugin afterwards.

Now we have "ureadable data" and are unsure if we can delete that, or if there is a problem with a plugin and muts fix that.

The warning message is "CannotResolveClassException: hudson.maven.reporters.MavenArtifactRecord : hudson.maven.reporters.MavenArtifactRecord".

WARNING: Failed to resolve class
com.thoughtworks.xstream.mapper.CannotResolveClassException: hudson.maven.reporters.MavenArtifactRecord : hudson.maven.reporters.MavenArtifactRecord
at com.thoughtworks.xstream.mapper.DefaultMapper.realClass(DefaultMapper.java:68)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.DynamicProxyMapper.realClass(DynamicProxyMapper.java:71)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.PackageAliasingMapper.realClass(PackageAliasingMapper.java:88)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.ClassAliasingMapper.realClass(ClassAliasingMapper.java:86)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.ArrayMapper.realClass(ArrayMapper.java:96)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at hudson.util.XStream2$CompatibilityMapper.realClass(XStream2.java:249)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at hudson.util.xstream.MapperDelegate.realClass(MapperDelegate.java:43)
at com.thoughtworks.xstream.mapper.MapperWrapper.realClass(MapperWrapper.java:38)
at com.thoughtworks.xstream.mapper.CachingMapper.realClass(CachingMapper.java:56)
at com.thoughtworks.xstream.core.util.HierarchicalStreams.readClassType(HierarchicalStreams.java:29)
at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.readItem(AbstractCollectionConverter.java:70)
at hudson.util.RobustCollectionConverter.populateCollection(RobustCollectionConverter.java:85)
at com.thoughtworks.xstream.converters.collections.CollectionConverter.unmarshal(CollectionConverter.java:61)
at hudson.util.RobustCollectionConverter.unmarshal(RobustCollectionConverter.java:76)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:82)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:63)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:76)
at hudson.util.RobustReflectionConverter.unmarshalField(RobustReflectionConverter.java:332)
at hudson.util.RobustReflectionConverter.doUnmarshal(RobustReflectionConverter.java:274)
at hudson.util.RobustReflectionConverter.unmarshal(RobustReflectionConverter.java:221)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:82)
at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:63)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:76)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:60)
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:137)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:33)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:926)
at hudson.util.XStream2.unmarshal(XStream2.java:103)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:912)
at hudson.XmlFile.unmarshal(XmlFile.java:160)
at hudson.model.Run.reload(Run.java:291)
at hudson.model.Run.<init>(Run.java:280)
at hudson.model.AbstractBuild.<init>(AbstractBuild.java:179)
at hudson.maven.AbstractMavenBuild.<init>(AbstractMavenBuild.java:54)
at hudson.maven.MavenBuild.<init>(MavenBuild.java:108)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at hudson.model.AbstractProject.loadBuild(AbstractProject.java:1078)
at hudson.model.AbstractProject$1.create(AbstractProject.java:277)
at hudson.model.AbstractProject$1.create(AbstractProject.java:275)
at hudson.model.RunMap.retrieve(RunMap.java:220)
at hudson.model.RunMap.retrieve(RunMap.java:59)
at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:638)
at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:621)
at jenkins.model.lazy.AbstractLazyLoadRunMap.search(AbstractLazyLoadRunMap.java:432)
at jenkins.model.lazy.AbstractLazyLoadRunMap.newestBuild(AbstractLazyLoadRunMap.java:297)
at hudson.model.AbstractProject.getLastBuild(AbstractProject.java:1015)
at hudson.maven.AbstractMavenProject.createTransientActions(AbstractMavenProject.java:184)
at hudson.model.AbstractProject.updateTransientActions(AbstractProject.java:682)
at hudson.maven.MavenModule.updateTransientActions(MavenModule.java:411)
at hudson.model.AbstractProject.onLoad(AbstractProject.java:301)
at hudson.maven.MavenModule.onLoad(MavenModule.java:236)
at hudson.model.Items.load(Items.java:221)
at hudson.model.ItemGroupMixIn.loadChildren(ItemGroupMixIn.java:99)
at hudson.maven.MavenModuleSet.onLoad(MavenModuleSet.java:738)
at hudson.model.Items.load(Items.java:221)
at jenkins.model.Jenkins$17.run(Jenkins.java:2507)
at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:146)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:259)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:883)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:187)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Nov 23, 2012 12:55:07 PM hudson.util.RobustCollectionConverter populateCollection

Can we remove that data?