If SSL was not enabled for your ServiceNow Connector instance, the following error will occur:
In Enterprise Manager: Connection test failed, check the OMS log files for details. The configuration was saved. The entry in the OMS log should look like this:
oracle.sysman.emSDK.webservices.outbound.WSInvokeException: caught WebServiceException : javax.xml.soap.SOAPException: javax.xml.soap.SOAPException: Message send failed: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
In ServiceNow: No error is displayed.
Solution: Add the Root Certificate as describe in Enabling SSL for HTTPS.