If you get an error message trying to start JMS-Server in JDeveloper like:

(SEVERE) Failed to set the internal configuration of the OC4J JMS Server with:

  1. Firstly check whether the port (default 9127) is not used/locked by other app.
  2. Try deleting the contents in your local OC4J path:

    When OC4J will start again, it will reset the local configurations and let JMS-Server start as normal.


credit: forums.oracle.com