EM 13.5: SAML SSO Login Fails with 403--Forbidden Error, Cannot get a valid certificate in partner registry to verify for partner SAML_SSO_IDP (Doc ID 2972082.1)

Error 403--Forbidden
From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:
10.4.4 403 Forbidden

The server understood the request, but is refusing to fulfill it. Authorization will not help and the request SHOULD NOT be repeated. If the request method was not HEAD and the server wishes to make public why the request has not been fulfilled, it SHOULD describe the reason for the refusal in the entity. This status code is commonly used when the server does not wish to reveal exactly why the request has been refused, or when no other response is applicable.

java.security.cert.CertificateExpiredException: NotAfter: Thu Jul 13 18:47:55 UTC 2023
at sun.security.x509.CertificateValidity.valid(CertificateValidity.java:277)
at sun.security.x509.X509CertImpl.checkValidity(X509CertImpl.java:677)
....
.....
<[Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:096549]Cannot get a valid certificate in partner registry to verify for partner SAML_SSO_IDP.>
javax.security.auth.login.LoginException: [Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:090377]Identity Assertion Failed, weblogic.security.spi.IdentityAssertionException: [Security:096549]Cannot get a valid certificate in partner registry to verify for partner SAML_SSO_IDP.
at com.bea.common.security.internal.service.IdentityAssertionServiceImpl.assertIdentity(IdentityAssertionServiceImpl.java:89)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)