X509: certificate signed by unknown authority

Elastic Stack Elastic Agent
4

Apologies I am unclear what "add host" means So this is about installing and non-fleet / regular agent?

I think you can copy the CA to the host where the agent is and then use this, I am not sure if that is the Fleet CA or the Elasticsearch CA you could try both.

elastic-agent install --url <string>
                      --enrollment-token <string>
                      [--ca-sha256 <string>] < - This or Below 
                      [--certificate-authorities <string>] <!--- THIS I Think, but this is the CA 
                      [--delay-enroll]
                      [--force]
                      [--non-interactive]
                      [--help]
                      [--insecure ]
                      [--tag <string>]
                      [global-flags]