My EJB passivates, but get this error when it tried to activate:

javax.ejb.EJBException: Could not activate; failed to restore state; CausedByException is:      C:\java\jboss-3.2.3\server\default\tmp\sessions\ClientSession-dyk88oym-4\dyk9fq8i-a6.ser (The system cannot find the file specified)      at org.jboss.ejb.plugins.StatefulSessionFilePersistenceManager.activateSession(StatefulSessionFilePersistenceManager.java:324)      at org.jboss.ejb.plugins.StatefulSessionInstanceCache.activate(StatefulSessionInstanceCache.java:90)      at org.jboss.ejb.plugins.AbstractInstanceCache.get(AbstractInstanceCache.java:107)      at org.jboss.ejb.plugins.StatefulSessionInstanceInterceptor.invoke(StatefulSessionInstanceInterceptor.java:210)

This was due to an EJB instance being passivated to a file (.ser) and then later that file being removed by a clean up service.  When the EJB instance was then called on to be activated, it�s serialized form on file was not there.  This was resolved by increasing the max-bean-life configuration parameter to a larger value so that would ensure any long running request would be completed before the clean up service would run on it.