Exception thrown during passivation

here's the trace :

11:22:13,468 WARN [UserManagerImpl] trying to authenticate against null username and/or password
11:22:13,484 ERROR [SimpleStatefulCache] problem passivation thread
java.lang.RuntimeException: javax.ejb.EJBAccessException: Authentication failure
at org.jboss.ejb3.interceptor.LifecycleInterceptorHandler.prePassivate(LifecycleInterceptorHandler.java:160)
at org.jboss.ejb3.stateful.StatefulContainer.invokePrePassivate(StatefulContainer.java:340)
at org.jboss.ejb3.stateful.StatefulBeanContext.prePassivate(StatefulBeanContext.java:178)
at org.jboss.ejb3.cache.simple.StatefulSessionFilePersistenceManager.passivateSession(StatefulSessionFilePersist
enceManager.java:328)
at org.jboss.ejb3.cache.simple.SimpleStatefulCache.passivate(SimpleStatefulCache.java:194)
at org.jboss.ejb3.cache.simple.SimpleStatefulCache$SessionTimeoutTask.run(SimpleStatefulCache.java:129)
Caused by: javax.ejb.EJBAccessException: Authentication failure
at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.handleGeneralSecurityException(Ejb3AuthenticationInterc
eptor.java:68)
at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:71)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:47)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
at org.jboss.ejb3.stateful.StatefulContainer.localInvoke(StatefulContainer.java:188)
at org.jboss.ejb3.stateful.StatefulLocalProxy.invoke(StatefulLocalProxy.java:98)
at $Proxy295.removeCacheListener(Unknown Source)
at org.nuxeo.ecm.webapp.cache.CacheUpdateNotifier$$FastClassByCGLIB$$304526a0.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.jboss.seam.intercept.RootInvocationContext.proceed(RootInvocationContext.java:45)
at org.jboss.seam.intercept.ClientSideInterceptor$1.proceed(ClientSideInterceptor.java:73)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:55)
at org.jboss.seam.interceptors.RemoveInterceptor.removeIfNecessary(RemoveInterceptor.java:39)
at sun.reflect.GeneratedMethodAccessor136.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.jboss.seam.util.Reflections.invoke(Reflections.java:18)
at org.jboss.seam.intercept.Interceptor.aroundInvoke(Interceptor.java:169)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:64)
at org.jboss.seam.interceptors.ExceptionInterceptor.handleExceptions(ExceptionInterceptor.java:38)
at sun.reflect.GeneratedMethodAccessor126.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.jboss.seam.util.Reflections.invoke(Reflections.java:18)
at org.jboss.seam.intercept.Interceptor.aroundInvoke(Interceptor.java:169)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:64)
at org.jboss.seam.interceptors.SynchronizationInterceptor.serialize(SynchronizationInterceptor.java:30)
at sun.reflect.GeneratedMethodAccessor125.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.jboss.seam.util.Reflections.invoke(Reflections.java:18)
at org.jboss.seam.intercept.Interceptor.aroundInvoke(Interceptor.java:169)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:64)
at org.jboss.seam.intercept.RootInterceptor.createSeamInvocationContext(RootInterceptor.java:144)
at org.jboss.seam.intercept.RootInterceptor.invokeInContexts(RootInterceptor.java:129)
at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:102)
at org.jboss.seam.intercept.ClientSideInterceptor.interceptInvocation(ClientSideInterceptor.java:82)
at org.jboss.seam.intercept.ClientSideInterceptor.intercept(ClientSideInterceptor.java:51)
at org.nuxeo.ecm.webapp.cache.CacheUpdateNotifier$$EnhancerByCGLIB$$21a56799.removeCacheListener(<generated>)
at org.nuxeo.ecm.webapp.navigation.TreeManagerBean.saveState(TreeManagerBean.java:356)
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.jboss.ejb3.interceptor.LifecycleInvocationContextImpl.proceed(LifecycleInvocationContextImpl.java:159)
at org.jboss.seam.intercept.EJBInvocationContext.proceed(EJBInvocationContext.java:37)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:55)
at org.jboss.seam.intercept.Interceptor.prePassivate(Interceptor.java:190)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:67)
at org.jboss.seam.intercept.Interceptor.prePassivate(Interceptor.java:190)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:67)
at org.jboss.seam.intercept.Interceptor.prePassivate(Interceptor.java:190)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:67)
at org.jboss.seam.intercept.Interceptor.prePassivate(Interceptor.java:190)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:67)
at org.jboss.seam.intercept.RootInterceptor.createSeamInvocationContext(RootInterceptor.java:144)
at org.jboss.seam.intercept.RootInterceptor.invokeInContexts(RootInterceptor.java:129)
at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:112)
at org.jboss.seam.intercept.RootInterceptor.invokeAndHandle(RootInterceptor.java:80)
at org.jboss.seam.intercept.SessionBeanInterceptor.prePassivate(SessionBeanInterceptor.java:55)
at sun.reflect.GeneratedMethodAccessor501.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.jboss.ejb3.interceptor.LifecycleInvocationContextImpl.proceed(LifecycleInvocationContextImpl.java:131)
at org.jboss.ejb3.interceptor.LifecycleInterceptorHandler.prePassivate(LifecycleInterceptorHandler.java:156)
... 5 more
Caused by: javax.security.auth.login.FailedLoginException: Username/password authentication failed for username: null, p
assword given: no
at org.nuxeo.ecm.platform.login.JBossLoginModule.login(JBossLoginModule.java:186)
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 javax.security.auth.login.LoginContext.invoke(LoginContext.java:769)
at javax.security.auth.login.LoginContext.access$000(LoginContext.java:186)
at javax.security.auth.login.LoginContext$4.run(LoginContext.java:683)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.login.LoginContext.invokePriv(LoginContext.java:680)
at javax.security.auth.login.LoginContext.login(LoginContext.java:579)
at org.jboss.security.plugins.JaasSecurityManager.defaultLogin(JaasSecurityManager.java:601)
at org.jboss.security.plugins.JaasSecurityManager.authenticate(JaasSecurityManager.java:535)
at org.jboss.security.plugins.JaasSecurityManager.isValid(JaasSecurityManager.java:344)
at org.jboss.aspects.security.AuthenticationInterceptor.authenticate(AuthenticationInterceptor.java:121)
at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:67)
... 71 more
Caused by: javax.security.auth.login.LoginException: invalid username or password
at org.nuxeo.ecm.platform.login.JBossLoginModule.validateUsernamePassword(JBossLoginModule.java:227)
at org.nuxeo.ecm.platform.login.JBossLoginModule.login(JBossLoginModule.java:180)
... 86 more

It doesn't seem to block any functionnality but may be it's worse than it seems....