When Jira attempts to connect to an SSL-protected service, it will first check whether the target service's certificate can be trusted. This is done by checking to see whether the certificate is present in what is called the Java trust store. If the certificate is not present, the connection will fail.

The trust store is a special KeyStore repository, usually called cacerts, and is located in the $JAVA_HOME/lib/security directory on the server.

We used the keytool utility to import the certificate to our local trust store, so the target service will be registered as a trusted service and will allow Jira to connect to it successfully.