Summary
The SAML service provider authentication request fails, and a warning message is displayed as Invalid resource key: ACS URL in unsigned request could not be verified.

Products
Access Manager (NAM)

Environment
Access Manager 4.5.3.1
Microsoft Windows Server 2016

Situation
The SAML Authentication Request gets rejected with the below message in a stdout.log file.
Warning: Invalid resource key: No endpoint defined for AuthnResponse. No prefix!
IDP initiated with a similar to the following SAML request, but did not exchange.
GET https://<IDP>/nidp/saml2/idpsend?PID=<ID>
Adding the "IGNORE_ACS_METADATA_CHECK = true" option did not resolve the at this time.

Resolution
Access Manager 5.0.3 for Linux resolved the issue. If you have difficulties migrating to Access Manager 5.0.3 OR if you are on Windows, please contact Technical Support for assistance as a patch may be available for Access Manager 4.5.6.

Knowledge Base Article Link

URL Name
KM000015354