the first pls.... SSL Problem Received fatal alter: unknown_ca


My Elasticsearch version 6.1.1, search guard 6.1.1-22.3, opendjdk-8 and ubutu 16.04, installed search guard

before testing the terminal shows until the white bar, I input the firefox to “https://localhost:9200”, then pops up and message “SSL Problem Recived fatal alter: unknown_ca”

what is solve this problem?

thank for read message