You certainly noticed a lot of Closure related tests fail. A few because of unavailable BlockContext API in BlockClosure... (most are fixed yet) But mainly because of tests messing with: MethodContext>>#runSimulated:contextAtEachStep: I think something is broken there... One missing or not up to date change from Eliot probably. Also there is a problem in the debugger: when halted in a Closure, executing restart then proceed won't restart correclty: Example: 1) Execute this : (ScriptLoader new buildConfigurationMapFor: #('foobar.blast')) load 2) Open the debugger (click debug) 3) select top but one context [] in ScriptLoader>>buildConfigurationMapFor: 4) click restart, then proceed You get Character doesNotUnderstand: #encodeForHttp a real mess, as if evaluating the code in wrong context...