Problem:
When doing Federation IDP initiated transaction, after the successfull authentication, we are getting redirected to the /redirect/redirect.jsp and looping.
In the FWSTrace.log we can see:
[SSO.java][processRequest][Current session state is: false]
[SSO.java][processRequest][Current session is not a valid session.]
[SSO.java][processRequest][Session cookie does not exists. redirecting to authentication url [CHECKPOINT = SSOSAML2_AUTHENTICATIONURL_REDIRECT]]
Solution:
Checking the ACO for Disablesessionvars=no fixed the problem.
Indeed, the Webagent should set the default session variables in order to propagate them to the Webagent Option pack.