AFAIK, Guvnor doesn't need the classes definition to open the process. It does need it for building the full package though. So maybe you are facing a different problem here. Do you see any error message or stack-trace in the log of your application server? If you want to upload the model jar into Guvnor you have to go to "Knowledge Bases" section in the left menu and do: Create New -> Upload Pojo Model After that, you need to compile your package: click on the package -> (if you are using 5.3 version of Guvnor, you must go to "Edit" tab) -> Build Package