I could not find what was the problem. /Users/ducasse/Documents/Pharo/images/P8Evaluator/P8Evaluator.image Pharo8.0.0 Build information: Pharo-8.0.0+build.247.sha.57e3eb84cac4564882b47b87e2a977199fbe2470 (64 Bit) Unnamed May be Spec2 side effect. Good news - reproducible - can stop with cmd . https://github.com/pharo-project/pharo/issues/3275 Stef