IDP3.2.1 Unable to decode incoming request

[Peter Schober]

* Cantor, Scott <cantor.2 at osu.edu> [2016-07-12 14:18]:
> That's your container malfunctioning. The IdP doesn't have any
> involvement in the session in question, it's the standard Java
> container session. If that's not working properly, your container is
> at fault.

Does the IDPv3 need container sessions now? I.e., stuff breaks if I
added cookies="false" to my context deployment fragment?
-peter