Hi, I tried to run tests in Pharo 1.1 #11275 and then I got an error when trying to open Message Names. The reason is that if you evaluate Smalltalk classNames includes: #C1 you got true so Smalltalk classNames includes it however it is not present in Smalltalk globals. After Smalltalk flushClassNameCache the problem disapeared. If I tried to create a class named SomeClass, the result was: Smalltalk classNames includes: #SomeClass -> false Smalltalk globals at: #SomeClass -> SomeClass I had to remove Object>>#initialExtent because of neverending deperecation warning (a methods tries respondsTo: #initialExtent on a model. I don't know which one because Recent Submissions doesn't work because of method reference AutoGeneratedClassForTestingSystemChanges>>#Comment anwered nil on actualClass message) -- Pavel