Hi, In the latest version of Pharo (Build 439 - sha 4810710), I would like to debug a startup script, but when I set up an halt in the method, the image is not able to start anymore... For example, when putting an halt in LanguageEnvironment class>>startUp self halt. self clearDefault. And restarting the image, I got this trace: [0mLanguageEnvironment class>>startUp LanguageEnvironment class(Behavior)>>startUp: ClassSessionHandler>>startup: [ :arg2 | arg2 startup: arg1 ] in WorkingSession>>runStartup: in Block: [ :arg2 | arg2 startup: arg1 ] [ arg2 value: arg3 ] in [ :arg3 | [ arg2 value: arg3 ] on: Exception do: [ :arg4 | self errorHandler handleError: arg4 ] ] in WorkingSession>>runList:do: in Block: [ arg2 value: arg3 ] BlockClosure>>on:do: [ :arg3 | [ arg2 value: arg3 ] on: Exception do: [ :arg4 | self errorHandler handleError: arg4 ] ] in WorkingSession>>runList:do: in Block: [ :arg3 | ... Array(SequenceableCollection)>>do: WorkingSession>>runList:do: WorkingSession>>runStartup: WorkingSession>>start: SessionManager>>launchSnapshot:andQuit: [ tmp3 := self launchSnapshot: arg1 andQuit: arg2. tmp1 signal ] in SessionManager>>snapshot:andQuit: in Block: [ tmp3 := self launchSnapshot: arg1 andQuit: arg2....etc... [ self value. Processor terminateActive ] in BlockClosure>>newProcess in Block: [ self value.... WorkingSession>> runList:do: should have catched the exception and opened the image, but I do not seems too.... What can I do to resolve this issue? I forgot to say that I am under Windows 10 ;) Thanks in advance for your help, Cheers, Vincent