Invalid change to class error when deploying EJB

Question

We have EJBs that were built by Webgain Visual Cafe and successfully deploy
to WLS 5.1. We then use the WLE EJB Deployer Tool to build WLE container
classes and deploy the same EJBs in WLE 5.1.
One EJB does not deploy in WLE. The ULOG error message is:
133929.EA-LAWSTUC!JavaServer.517: main: IJENGINE_CAT:150: ERROR: Invalid
change to class service.Request
133929.EA-LAWSTUC!JavaServer.517: main: EJB_CAT:29: ERROR: While deploying
jar ServiceEJB : com.beasys.weblogic.classloader.RedeploymentException:
ERROR: Invalid change to class service.Request
133929.EA-LAWSTUC!JavaServer.517: Finalizer: IJENGINE_CAT:152: INFO: Closing
jar C:\aj\ServiceEJB_WLE.jar
Does anyone know what can cause an "invalid change to class" error when
deploying to WLE 5.1? Especially since the EJB deploys successfully in
WLS.
Carl Lawstuen

Answer 1

Reason: database keeps a reference of the class in JAVA$CLASS$MD5$TABLE table. This table keeps a refrence to all java classes loaded in database, and is present in each schema you deploy classes. That's the reason why if you change the application module name, you can load this classes. It instead keeps a reference if you use DROP JAVA CLASS command to drop a java class from de database. Use DROP JAVA command to clear the reference of the dropped classes when dropping it.
You can see this table as a class dictionary of the database, and you don't have to handle this records manually.