I got this error when public to Orchestrator on-premise.
Please help. Thanks
Can you clarify when you are seeing that error message and where? It sounds like you are connecting to Orchestrator (Web UI, Robot?).
Have you configured a certificate for use and is that certificate or certificate chain trusted by the client computer you are connecting from?
If you are using a self-signed certificate, you will need to import it in every robot or client host. If you are on a domain make sure the certificate is signed by your Root CA or a trusted CA in the certificate chain.
More details can be found here