I would like to know what are the changes I will have to make in the application running in weblogic 9.2 to make it run in weblogic 12c. Any link will be of great help
Firstly, look for a suitable IDE that supports WebLogic 12c. Import your code into the IDE. Build and check for the Warnings and errors. Solve the corresponding errors and warnings, build and keep checking for Errors and Warnings simultaneously.
Try solving any particular module of your application first to check whether the above methodology is working in your case or not.