Hi, The RB refactorings do some obscure dance around an errorBlock, which is always nil, as far as I can see. As I was trying to supply a non-nil error block, I was astonished to find out that even if it isn't nil, it won't be executed. Here's the relevant snippets: checkPreconditions | conditions block | conditions := self preconditions. conditions check ifFalse: [block := conditions errorBlock. block notNil ifTrue: [self refactoringError: conditions errorString with: block] ifFalse: [self refactoringError: conditions errorString]] refactoringError: aString with: aBlock ^ RefactoringError signal: aString with: aBlock I can't imagine how that could help anyone. I suggest either removing the errorBlock, or turning it into a good old instance variable, and running it in case of an error. Cheers, Niko -- http://scg.unibe.ch/staff/Schwarz twitter.com/nes1983 Tel: +41 076 235 8683