Shibboleth 2.5.3 SP looping after successful POST

[Peter Schober]

* James W. Anderson <jamesanderson at coca-cola.com> [2016-10-21 21:42]:
> When I hit the site, Shibboleth returns an AuthnRequest and
> redirects me to the IDP, the IDP authenticates me, my browser POSTs
> the assertion back to the ACS URL on the site, the POST returns a
> 302 and redirects me to the root of the site. At this point,
> Shibboleth returns another AuthnRequest and the process begins all
> over again.

https://wiki.shibboleth.net/confluence/display/SHIB2/Troubleshooting
-> "Native Service Provider (SP)" -> "Looping"
https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPLooping

HTH,
-peter