Hi, (yep, I'm copying tree lists because I think is a vm problem, but can be a seaside problem, or a pharo problem) (yes, it can be MY problem too... but I don't think so... ;) I'm having this really, really strange problem (because it was working before, and I do not change anything... so, maybe a change in latest changes on pharo 1.3, the version I'm using, is the cause)... This is the problem: I'm creating an application who sends an announcement, to edit something... this announcement ends in a WAComponent>>#call: message... The problem is: continuation execution fires a notification (WARenderNotification), and SubscriptionRegistry>>deliver:to: process the announcement this way: deliver: anAnnouncement to: subs subs do: [:each | [each deliver: anAnnouncement] "each is always in subs, so error will be due to each being last element. So return, nothing more to process" ifCurtailed: [self deliver: anAnnouncement to: ([subs after: each] on: NotFound do: [^self])]] ...and curtailedBlock is being executed... and that throws an error. This was working on older versions of VM, so maybe this is a recent change? this error was confirmed in my builds, and also in latest Eliot build. Also... is confirmed NOT being there in older cogs or interpreter. and btw... self deliver: anAnnouncement to: ([subs after: each] on: NotFound do: [^self]) shouldn't be self deliver: anAnnouncement to: ([Array with: (subs after: each)] on: NotFound do: [^self]) because #deliver:to: is expecting a collection, not a registry? thanks, Esteban