Deploying composite from jDeveloper throws error: oracle.ide.ceditor.CodeEditorScrollableSectionView cannot be cast to oracle.tip.tools.ide.fabric.gui.components.DiagramEditor

I want to bet this is one of the first errors a developer runs into when working with BPEL. When you try to build a .jar file or deploy your composite from jDeveloper to the application server it suddenly pops up in your deployment log and your deployment is cancelled. To rule out randomness you try again, but BOOM! Alas, there it is again:

[11:54:05 AM] Deployment cancelled.

[11:54:06 AM] ----  Deployment incomplete  ----.

[11:54:06 AM] Unable to package module

[11:54:06 AM] oracle.ide.ceditor.CodeEditorScrollableSectionView cannot be cast to oracle.tip.tools.ide.fabric.gui.components.DiagramEditor

This has to do with your composite.xml not being in Design mode at the time of the build. Also, if you closed the composite.xml while it was in Source mode it will stay in Source mode. Put it back in Design mode, try again and you will see that deployment will now be successful.

The reason seems to be that after the build, jDeveloper will view the diagram from Design mode. If Source mode is the active tab, it will fail to do so.