Post renewal of certificate on Production, agents not connecting

Products

• CA Application Performance Management (APM / Wily / Introscope)

Issue/Introduction

Stopped all the collectors and restarted the collector where new certificate was added and saw the below errors in the logs.

 [DEBUG] [Connection Helper 2] [Manager.IncomingConnectionListener] Incoming Connection threw exception.  This may happen normally when a Workstation logs in: javax.net.ssl.SSLHandshakeException: Received fatal alert: certificate_unknown

Resolution

Made the change in the certificate with root and imported the agent side certificate in a single certificate. After  that, all is working fine in collector.

Additional Information

May have to add the cert to the keystore and truststore. (And Java keystore) to resolve this.