Hi, I just tried to enable Pharo64-10 (not Pharo64-10.0 but that is probably another issue) in a GitHub Action CI using SmalltalkCI. https://github.com/svenvc/ston/blob/master/.github/workflows/CI.yml https://github.com/svenvc/ston/runs/5286121566?check_suite_focus=true This fails with NotFound: [ :cl | cl isPlatformCompatible ] not found in OrderedCollection OrderedCollection(Collection)>>errorNotFound: [self errorNotFound: aBlock] in OrderedCollection(Collection)>>detect: in Block: [self errorNotFound: aBlock] OrderedCollection(Collection)>>detect:ifFound:ifNone: OrderedCollection(Collection)>>detect:ifNone: OrderedCollection(Collection)>>detect: SmalltalkCI class>>platformClass ... Does anyone have any idea ? I seem to remember there were some issue with Metacello attributes, but maybe that is not related. Sven PS: I could try with other repositories but that will probably give the same result. Only Zinc does run with Pharo 10, last build a day ago. I can't spot the difference.