Hi, I'm getting crazy about obsolete behaviors and any help here is really appreciated. In a nutshell, I have a Dictionary (containing receivers of method calls, i.e., classes) that I need to serialize in a file (i.e., using Fuel). Fuel returns an error in FLGlobalClassCluster>>#serializeGlobalClass:on: complaining that I'm trying to serialize an obsolete class. Now my question is, apart from executing this small piece of code... SmalltalkImage current fixObsoleteReferences. SystemNavigation new obsoleteBehaviors size > 0 ifTrue: [ SystemNavigation new obsoleteBehaviors inspect.] â¦in which I discovered to have many obsolete references, how can I "browse" and eventually kill such references? For me the entire "behavior" of obsolete classes is obscure and I don't know how those classes are originated. More important, I also don't know how to eliminate them. Thanks in advance, Roberto