The following is run but almost immediately terminates without any errors. WHY? I used "twistd -noy server.tac". Here is the code: **************************** import twisted from twisted.spread import pb from twisted.cred import checkers,portal from twisted.internet import reactor from twisted.python import threadable from twisted.python import usage import threading import socket clients={} class ClientRemoteObject(pb.Avatar): global clients def __init__(self): print "ClientRemoteObject initialized." def attached(self): print "Client attached" return self def detached(self): print "Client detached" def perspective_initialDataExchange(self,clientreference,username): print "Client reference attached for:" + username clients[username]=clientreference data={} data['connected']=1 return data def perspective_broadcastMessage(self,msg): for user in clients: clients[user].callRemote("messageCB",msg + "s") class DefaultRealm: __implements__ = portal.IRealm def requestAvatar(self, avatarID, mind, *interfaces): assert pb.IPerspective in interfaces clientremoteobj = ClientRemoteObject() clientremoteobj.attached() return pb.IPerspective, clientremoteobj, lambda a=clientremoteobj:a.detached() def shutdownCleanUp(): print "Twisted reactor shutting down." application = twisted.application.service.Application("server01") myService = twisted.application.service.IServiceCollection(application) reactor.addSystemEventTrigger('before','shutdown',shutdownCleanUp) p = portal.Portal(DefaultRealm()) dbu=twisted.cred.checkers.InMemoryUsernamePasswordDatabaseDontUse() dbu.addUser("user1","pass1") p.registerChecker(dbu) myServer = twisted.application.internet.TCPServer(81,pb.PBServerFactory(p)) myServer.setServiceParent(myService) **************** It used to work with Twisted 1.3rc1, but it does not run with Twisted 2.2 (or 2.3 or 2.4). I am using Python 2.3, and running this from a DOS prompt in Windows.