A Reltio-defined procedure was used to set up SAML SSO: https://docs.reltio.com/security/ssocustconfig.html
But it is still not working while logging into the tenant and the user is getting the error "External IdP Error:null".
1. Check the configuration.xml file which was used for SSO configuration.
At the first line it says:
<EntityDescriptor xmlns="urn:oasis:names:tc:SAML:2.0:metadata" ID="..." entityID="https://gpl.tst...." validUntil="2018-10-23T19:01:42.120+00:00">
2. Make sure that ValidUntil does not have a past date.
If it has a past date, then ask the IDP provider to share a new metadata file with a future date or an unlimited expiration date.