Before upgrading to any release post-Orlando, the SSO is working fine.
But after the upgrade to Paris/Quebec version, the SSO is not working as expected on that same instance.
All releases before and including Orlando.
Before the release of 'Paris', we were using 3 different plugins for enabling Single Sign-On on the instance. See the screenshot)
This feature was updated in releases post-Orlando release (Paris, Quebec, etc.) where we are now using one streamlined plugin for enabling SSO ie. 'Integration - Multiple Provider Single Sign-On Installer'
Also, the SSO configuration options were updated for enabling SSO and configuring SSO and other options in the Filter Navigator.
After you update the instance to Paris release and later, to activate SSO again please do the following :
SSO should be working fine now after following the above steps and for additional setup please follow the below ServiceNow documentation: