Plugin respository exception

When trying to access the plugin repository it hangs on "Caching data". In the log I get :

[07-05-02 15:08:48:572 CEST] 00000027 SystemOut O 2007-05-02 15:08:48,572 WARN [WebContainer : 4] [getaheadplugin.dwr.impl.ExecuteQuery] warn Method execution failed:
– url: /wiki/plugins/servlet/plugin-repository/dwr/exec/RepositoryDWR.startCaching.dwr | userName: g9adm
com.thoughtworks.xstream.converters.ConversionException: : com.atlassian.plugin.repository.model.RepositoryCategory
---- Debugging information ----
cause-exception : com.thoughtworks.xstream.converters.reflection.ObjectAccessException
required-type : com.atlassian.plugin.repository.model.RepositoryCategory
class : com.atlassian.plugin.repository.model.RepositoryShuttle
message : : com.atlassian.plugin.repository.model.RepositoryCategory
line number : 4
path : /com.atlassian.plugin.repository.model.RepositoryShuttle/rootCategory
cause-message : : com.atlassian.plugin.repository.model.RepositoryCategory
-------------------------------
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:45)
at com.thoughtworks.xstream.core.ReferenceByXPathUnmarshaller.convertAnother(ReferenceByXPathUnmarshaller.java:39)
at com.atlassian.plugin.repository.utils.BestGuessReflectionConverter.unmarshal(BestGuessReflectionConverter.java:98)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:38)
at com.thoughtworks.xstream.core.ReferenceByXPathUnmarshaller.convertAnother(ReferenceByXPathUnmarshaller.java:39)
at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:99)
at com.thoughtworks.xstream.core.ReferenceByXPathMarshallingStrategy.unmarshal(ReferenceByXPathMarshallingStrategy.java:12)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:549)
at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:537)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:505)
at com.atlassian.plugin.repository.datasource.ProxyDataSource.getData(ProxyDataSource.java:93)
at com.atlassian.plugin.repository.datasource.ProxyDataSource.startCaching(ProxyDataSource.java:141)
at com.atlassian.plugin.repository.dwr.RepositoryDWR.startCaching(RepositoryDWR.java:66)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:615)
at uk.ltd.getaheadplugin.dwr.impl.ExecuteQuery.execute(ExecuteQuery.java:239)
at uk.ltd.getaheadplugin.dwr.impl.DefaultExecProcessor.handle(DefaultExecProcessor.java:48)
at uk.ltd.getaheadplugin.dwr.impl.DefaultProcessor.handle(DefaultProcessor.java:120)
at uk.ltd.getaheadplugin.dwr.AbstractDWRServlet.doPost(AbstractDWRServlet.java:162)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.atlassian.plugin.descriptors.servlet.ServletModuleContainerServlet.service(ServletModuleContainerServlet.java:38)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:989)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:930)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:145)
at com.atlassian.confluence.util.LoggingContextFilter.doFilter(LoggingContextFilter.java:46)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:182)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:159)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.confluence.util.ClusterHeaderFilter.doFilter(ClusterHeaderFilter.java:35)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:172)
at com.atlassian.spring.filter.FlushingSpringSessionInViewFilter.doFilterInternal(FlushingSpringSessionInViewFilter.java:29)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:122)
at com.atlassian.core.filters.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:27)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.confluence.util.RequestCacheThreadLocalFilter.doFilter(RequestCacheThreadLocalFilter.java:25)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.core.filters.gzip.GzipFilter.doFilter(GzipFilter.java:61)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:37)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:87)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:761)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:673)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:498)
at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:464)
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3184)
at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:254)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:811)
at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1433)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:111)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:454)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:383)
at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:102)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:136)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:195)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:873)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1469)
Caused by: com.thoughtworks.xstream.converters.reflection.ObjectAccessException: : com.atlassian.plugin.repository.model.RepositoryCategory
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.instantiateUsingSerialization(PureJavaReflectionProvider.java:95)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.newInstance(PureJavaReflectionProvider.java:48)
at com.atlassian.plugin.repository.utils.BestGuessReflectionConverter.instantiateNewInstance(BestGuessReflectionConverter.java:146)
at com.atlassian.plugin.repository.utils.BestGuessReflectionConverter.unmarshal(BestGuessReflectionConverter.java:85)
at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:38)
... 81 more
Caused by: java.lang.ClassNotFoundException: com.atlassian.plugin.repository.model.RepositoryCategory
at java.lang.Class.forNameImpl(Native Method)
at java.lang.Class.forName(Class.java:164)
at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:599)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1563)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1485)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1718)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1324)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:362)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.instantiateUsingSerialization(PureJavaReflectionProvider.java:91)
... 85 more
[07-05-02 15:08:48:587 CEST] 00000027 SystemOut O 2007-05-02 15:08:48,587 WARN [WebContainer : 4] [getaheadplugin.dwr.impl.DefaultExecProcessor] warn Erroring: id[5025_1178111438863] message[uk.ltd.getaheadplugin.dwr.OutboundVariable@4260426]