HibernatePersistenceProvider fails with java.lang.Integer version check ----------------------------------------------------------------------- Key: JBSEAM-2389 URL: https://issues.jboss.org/browse/JBSEAM-2389 Project: Seam 2 Issue Type: Bug Components: Core Reporter: Christian Bauer Priority: Critical My entity had a version property: @Version @Column(name = "OBJ_VERSION", nullable = false) protected Integer version; In a very involved ajax reRender/conversation situation I sometimes got the following exception from HibernatePersistenceProvider: public static void checkVersion(Object value, Session session, Object oldVersion, Object version) { ClassMetadata classMetadata = getClassMetadata(value, session); VersionType versionType = (VersionType) classMetadata.getPropertyTypes()[ classMetadata.getVersionProperty() ]; if ( !versionType.isEqual(oldVersion, version) ) { throw new StaleStateException("current database version number does not match passivated version number"); } } This failed because oldVersion was 'null' and version was '0'. Hibernate returned '0' from ClassMetaData.getVersion(), it looks like it can't return null, from Javadoc: Get the version number (or timestamp) from the object's version property (or return null if not versioned). We should do a null check before asking Hibernate. Workaround: Use primitive for version field in entity or initialize it to '0'.