so once again rpackage is registered to the wrong announcer... I figured out that update 20200 first introduced this bug by wrongly resetting RPackage: http://code.google.com/p/pharo/issues/detail?id=6326 It registered RPackageOrganizer to MCWorkingCopy announcer but SystemAnnouncer announcer == MCWorkingCopy announcer and by default RPackageOrganizer registers to SystemAnnouncer privateAnnouncer. obviously we got a double registration of RPackageOrganizer after this. Which can be easily fixed by doing: RPackageOrganizer registerInterestToSystemAnnouncement. The invariant that should hold is self assert: SystemAnnouncer announcer hasSubscriber: RPackageOrganizer default = false. self assert: SystemAnnouncer privateAnnouncer hasSubscriber: RPackageOrganizer default. however I still can't figure out where the damn bug got introduced again...