Hi, I have a product with a container class to save a list of groups and others objects.. The container class is: class StorageAdapter(ObjectManager, BasicUserFolder): .... .... this class have a function to add groups like that: def addGroup(self, id="", nombre="", REQUEST =None): """to add a new group""" #create a group grupo = Group(id, nombre) #add a group to container try: self._objects=self._objects+ ({'id':id,'meta_type':Group.meta_type},) self._setOb(id,grupo) object=self._getOb(id) self._p_changed = 1 except: return MessageDialog( title ='error', message='error al añadir grupo', ) if REQUEST is not None: REQUEST['RESPONSE'].redirect(self.absolute_url()+'/gestGroupForm') The class group is simple like this. class Group(ObjectManager, BasicUserFolder): """Class Group""" meta_type = 'Group' title ='Grupo' def __init__(self, id, nombre): _debug("init del Group") self.id=id self.nombre=nombre #acl to control this group f=AclUserFolder() _debug("creo el acl del Group") try: self._setObject('acl_users', f) except: return MessageDialog( title ='error Acl Existente', message='Este Group ya contiene un ACL', ) self.__allow_groups__=self.acl_users ... ... ... the function addGroup is called from a dtml and the groups are added ok and later I can view the result perfectly in dtml, but i want to add a new attribute to class group then in the method __init__ i have add the sentence: self.contacts=[] this is the only change and then i obtain this error: 2006-05-22T16:29:14 ERROR Zope.SiteErrorLog http://localhost:8080/prueba/ST/addGroup Traceback (most recent call last): File "/usr/lib/zope/lib/python/ZPublisher/Publish.py", line 119, in publish transactions_manager.commit() File "/usr/lib/zope/lib/python/Zope2/App/startup.py", line 234, in commit transaction.commit() File "/usr/lib/zope/lib/python/transaction/_manager.py", line 84, in commit self.get().commit(sub) File "/usr/lib/zope/lib/python/transaction/_transaction.py", line 381, in commit self._saveCommitishError() # This raises! File "/usr/lib/zope/lib/python/transaction/_transaction.py", line 379, in commit self._commitResources() File "/usr/lib/zope/lib/python/transaction/_transaction.py", line 424, in _commitResources rm.commit(self) File "/usr/lib/zope/lib/python/ZODB/Connection.py", line 462, in commit self._commit(transaction) File "/usr/lib/zope/lib/python/ZODB/Connection.py", line 503, in _commit self._store_objects(ObjectWriter(obj), transaction) File "/usr/lib/zope/lib/python/ZODB/Connection.py", line 525, in _store_objects p = writer.serialize(obj) # This calls __getstate__ of obj File "/usr/lib/zope/lib/python/ZODB/serialize.py", line 330, in serialize return self._dump(meta, obj.__getstate__()) TypeError: Can't pickle objects in acquisition wrappers. i don't known where can be my error, if someone can help me. thank jose carlos