After upgrading from 1.330 to 1.331, some projects fail to load. Reverting to
1.330 makes them reappear.

I have several kinds stack traces in the log, but they all have a
ClassCastException:

• ConversionException with DiskUsageProperty
  hudson.util.IOException2: Unable to read
  /usr/local/web/.hudson/jobs/project1/config.xml
  at hudson.XmlFile.read(XmlFile.java:130)
  at hudson.model.Items.load(Items.java:106)
  at hudson.model.Hudson$9.call(Hudson.java:2011)
  at hudson.model.Hudson$9.call(Hudson.java:2004)
  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
  at java.util.concurrent.FutureTask.run(FutureTask.java:138)
  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:619)
  Caused by: com.thoughtworks.xstream.converters.ConversionException:
  com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
  java.lang.ref.WeakReference :
  com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
  java.lang.ref.WeakReference
  • • • Debugging information ----
        message :
        com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
        java.lang.ref.WeakReference
        cause-exception : java.lang.ClassCastException
        cause-message :
        com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
        java.lang.ref.WeakReference
        class : hudson.model.FreeStyleProject
        required-type : hudson.util.CopyOnWriteList
        path :
        /project/properties/hudson.plugins.disk_usage.DiskUsageProperty
        line number : 10
        -------------------------------
        at
        com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:89)
        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
        hudson.util.RobustReflectionConverter.unmarshallField(RobustReflectionConverter.java:261)
        at
        hudson.util.RobustReflectionConverter.doUnmarshal(RobustReflectionConverter.java:221)
        at
        hudson.util.RobustReflectionConverter.unmarshal(RobustReflectionConverter.java:172)
        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:923)
        at hudson.util.XStream2.unmarshal(XStream2.java:70)
        at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:909)
        at com.thoughtworks.xstream.XStream.fromXML(XStream.java:853)
        at hudson.XmlFile.read(XmlFile.java:126)
        ... 8 more
        Caused by: java.lang.ClassCastException:
        com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
        java.lang.ref.WeakReference
        at
        com.thoughtworks.xstream.mapper.CachingMapper.realClass(CachingMapper.java:45)
        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.CopyOnWriteList$ConverterImpl.unmarshal(CopyOnWriteList.java:184)
        at
        hudson.util.CopyOnWriteList$ConverterImpl.unmarshal(CopyOnWriteList.java:163)
        at hudson.util.XStream2$AssociatedConverterImpl.unmarshal(XStream2.java:157)
        at
        com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:82)
        ... 25 more

• ConversionException with MonitorPublisher
  hudson.util.IOException2: Unable to read
  /usr/local/web/.hudson/jobs/project2/config.xml
  at hudson.XmlFile.read(XmlFile.java:130)
  at hudson.model.Items.load(Items.java:106)
  at hudson.model.Hudson$9.call(Hudson.java:2011)
  at hudson.model.Hudson$9.call(Hudson.java:2004)
  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
  at java.util.concurrent.FutureTask.run(FutureTask.java:138)
  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:619)
  Caused by: com.thoughtworks.xstream.converters.ConversionException:
  com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
  java.lang.ref.WeakReference :
  com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
  java.lang.ref.WeakReference
  • • • Debugging information ----
        message :
        com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
        java.lang.ref.WeakReference
        cause-exception : java.lang.ClassCastException
        cause-message :
        com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
        java.lang.ref.WeakReference
        class : hudson.maven.MavenModuleSet
        required-type : hudson.util.DescribableList
        path :
        /maven2-moduleset/publishers/hudson.plugins.statusmonitor.MonitorPublisher
        line number : 120
        -------------------------------
        at
        com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:89)
        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
        hudson.util.RobustReflectionConverter.unmarshallField(RobustReflectionConverter.java:261)
        at
        hudson.util.RobustReflectionConverter.doUnmarshal(RobustReflectionConverter.java:221)
        at
        hudson.util.RobustReflectionConverter.unmarshal(RobustReflectionConverter.java:172)
        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:923)
        at hudson.util.XStream2.unmarshal(XStream2.java:70)
        at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:909)
        at com.thoughtworks.xstream.XStream.fromXML(XStream.java:853)
        at hudson.XmlFile.read(XmlFile.java:126)
        ... 8 more
        Caused by: java.lang.ClassCastException:
        com.thoughtworks.xstream.mapper.CannotResolveClassException cannot be cast to
        java.lang.ref.WeakReference
        at
        com.thoughtworks.xstream.mapper.CachingMapper.realClass(CachingMapper.java:45)
        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.CopyOnWriteList$ConverterImpl.unmarshal(CopyOnWriteList.java:184)
        at
        hudson.util.DescribableList$ConverterImpl.unmarshal(DescribableList.java:312)
        at
        com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:82)
        ... 25 more

• shorter ConversionException on MonitorPublisher
  hudson.util.IOException2: Unable to read
  /usr/local/web/.hudson/jobs/project3/config.xml
  at hudson.XmlFile.read(XmlFile.java:130)
  at hudson.model.Items.load(Items.java:106)
  at hudson.model.Hudson$9.call(Hudson.java:2011)
  at hudson.model.Hudson$9.call(Hudson.java:2004)
  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
  at java.util.concurrent.FutureTask.run(FutureTask.java:138)
  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:619)
  Caused by: com.thoughtworks.xstream.converters.ConversionException: null : null
  • • • Debugging information ----
        cause-exception : java.lang.ClassCastException
        cause-message : null
        class : hudson.maven.MavenModuleSet
        required-type : hudson.util.DescribableList
        path :
        /maven2-moduleset/publishers/hudson.plugins.statusmonitor.MonitorPublisher
        line number : 68
        -------------------------------
        at
        com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:89)
        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
        hudson.util.RobustReflectionConverter.unmarshallField(RobustReflectionConverter.java:261)
        at
        hudson.util.RobustReflectionConverter.doUnmarshal(RobustReflectionConverter.java:221)
        at
        hudson.util.RobustReflectionConverter.unmarshal(RobustReflectionConverter.java:172)
        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:923)
        at hudson.util.XStream2.unmarshal(XStream2.java:70)
        at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:909)
        at com.thoughtworks.xstream.XStream.fromXML(XStream.java:853)
        at hudson.XmlFile.read(XmlFile.java:126)
        ... 8 more
        Caused by: java.lang.ClassCastException