Getting rid of “Unwriteable session” errors when running in development mod

When running my Vaadin application in development mode, I keep getting org.eclipse.jetty.server.session.UnwriteableSessionDataException: Unwriteable session exceptions. Looking down the stack trace, the exception is always caused by a of a view’s class member which is indeed not serializable. The members in question (service objects, beans actually) are marked as transient though so no attempt to serialize them should be made anyway?

Is there a way to fix this? It’s a nightmare when you need to debug and your log gets filled with non-informative stack traces (which are quite huge as well).

This is only a problem in development mode, I don’t see these problems when running in production mode.