Single Sign On Test connection is successful but during actual login user is immediately redirected to logout

Single Sign On Test connection is successful but during actual login user is immediately redirected to logout

Checking the system logs if you see the below error:

2019-11-14 11:35:33 (799) Default-thread-13 F48220FA1B498810D764759D1E4BCB71 txid=4492e4fa1b49 WARNING *** WARNING *** Evaluator: org.mozilla.javascript.EcmaError: "sessionIndex" is not defined.
Caused by error in Installation Exit: 'MultiSSO' at line 1
==> 1: gs.include("PrototypeServer");
2:
3: gs.include("MultiSSO_SAML2_Update1");
4: gs.include("MultiSSO_DigestedToken");

This indicates that SAML response does not contain "sessionIndex"
Sample attribute in SAML response that contains the SessionIndex
<saml2:AuthnStatement AuthnInstant="2019-11-15T20:05:07.158Z" SessionIndex="SNCf58ab2979adc3a4d30fa487bafb0847b">

Check with the  IDP admin and make sure that sessionindex is returned in the SAML response.