SOAP Adapter Runtime Connection Error When Using Private Endpoints

If you create a SOAP Adapter WSDL URL-based connection configured to use a private endpoint, the test connection on the Connections page is successful, but the runtime connection fails with the following error:

Exception occurred while invoking https://IP_Address:port/oraclediagent/OdiInvoke?wsdl:\noracle.cloud.connectivity.services.ConnectivityServiceException: null: Exception occurred while executing request 
https://IP_Address:port/oraclediagent/OdiInvoke?wsdl\n\tat oracle.cloud.adapter.rest.client.jersey.AdapterRestJersey2Client.execute(AdapterRestJersey2Client.java:133)\n\tat oracle.tip.tools.ide.adapters.cloud.impl.
util.rest.RESTHelper.executeRequest(RESTHelper.java:455)\n\tat oracle.tip.tools.ide.adapters.cloud.impl.util.rest.RESTHelper.invokeGet(RESTHelper.java:205)\n\tat oracle.tip.tools.ide.adapters.cloud.impl.util.rest.
RESTHelper.invokeGetRequest(RESTHelper.java:159)\n\tat oracle.cloud.connector.impl.CloudAdapterUtil.parseDefinition(CloudAdapterUtil.java:349)\n\tat oracle.cloud.connector.impl.CloudOperationImpl.parseTargetWSDL
(CloudOperationImpl.java:119)\n\tat oracle.cloud.connector.impl.CloudOperationImpl.<init>(CloudOperationImpl.java:79)\n\tat oracle.cloud.connector.impl.AbstractCloudApplicationConnection.getCloudOperation
(AbstractCloudApplicationConnection.java:35)\n\tat oracle.tip.adapter.cloud.CloudAdapterInteraction.createCloudOperation(CloudAdapterInteraction.java:411)\n\tat 
. . .
. . .
. . .
sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target\n\tat java.base/sun.security.ssl.Alert.createSSLException(Alert.java:130)\n\tat 
java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:378)\n\tat java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:321)\n\tat java.base/sun.security.ssl.TransportContext.
fatal(TransportContext.java:316)\n\tat java.base/sun.security.ssl.CertificateMessage$T13CertificateConsumer.checkServerCerts(CertificateMessage.java:1318)\n\tat java.base/sun.security.ssl.CertificateMessage$T13
CertificateConsumer.onConsumeCertificate(CertificateMessage.java:1195)\n\tat java.base/sun.security.ssl.CertificateMessage$T13CertificateConsumer.consume(CertificateMessage.java:1138)\n\tat java.base/sun.security.
ssl.SSLHandshake.consume(SSLHandshake.java:393)\n\tat 

To resolve this issue, import a self-signed certificate on the Certificates page.

See Upload a Certificate to Connect with External Services.