Jenkins installation has been running fine for a few months, using Azure AD version 0.3.1. Suddenly (first failure encountered on 30-SEP-2018 - was definitely working on 28-SEP-2018) all logins through Azure SSO fails with the "Oops!" Jenkins error and error message "java.security.cert.CertificateException: No subject alternative DNS name matching login.microsoftonline.com found."
Full stack trace is attached as "StackTrace.txt".
The Azure SSO account used for login works fine on the Azure portal and another internal site, so I do not suspect that the user account is the problem. I would suspect either an expired certificate somewhere or perhaps a policy change based on the current time?