There's a race condition in AbstractConversationContext when create first conversation scope if it's the first request of one session.
Suppose such scenario
# User requests a jsf page
# weld creates a conversations map in the AbstractConversationContext.associate()
# Because it is the first request, there's no session. Weld keep this map in request
A conversation scoped bean is created and put to the map.
In somewhere, a session is created
# In the render phase, server sends partial response back. The page need some jsf resource, eg, jsf2 ajax or jsf resource
# Browser requests the new jsf resource
# At this time The first request has not finished. So it doesn't reach dissociate() and doesn't put conversations map in the session.
# Meanwhile The second request reach associate(). There's no conversations map in the session, and the session is existing. It puts its new map! <====
# Then, even the first request finishes it's response and reach dissociate(), because there's already a map, it doesn't put its owner anymore. <====
A quick and dirty fix is always create session before associate(). However, it's better to merge the map in the dissociate()
I upload a example which is very easy to reproduce the problem.