Attempting to start the Applications Manager (AM) processes results in the following error message in the RmiServer log.
This error is usually caused if the RmiServer port defined is used by another process or custom SSL certificates for Connection Authentication are missing.
Applications Manager 9.3.5
Change the RmiRegistry port in the $AW_HOME/web/classes/Options.properties file to another unused port number, and restart the AM processes.
If error persists, check if you are using Custom SSL Certificates for Connection Authentication
With version 9.3.3 and higher, You must use a custom SSL certificate for connection authentication by creating user_keystore and user_keystore_config files on the Automation Engine machine as well as every remote agent and client machine. Using your own certificate prevents unauthorized connections between connection endpoints.
See documentation link below for details: