protected void Session_End(Object sender, EventArgs e) { string userName = Membership.GetUserNameByEmail(User.Identity.Name); Guid userId = Guid.Parse(Membership.GetUser(userName).ProviderUserKey.ToString()); ParticipantRepository participantRepository = new ParticipantRepository(); participantRepository.RemoveUserFromAllTubes(userId); HttpContext.Current.Cache[userId.ToString() + "online"] = false; }