Look in ~/Library/Logs/DiagnosticReports

@tig said: If the RB is going to be encrypted use this: ext = SketchupExtension.new(extensionName, "greenspaceLive_gModeller/LiveEnergy-Classes/main") SketchUp automatically finds a matching file RB or RBS... You never mentioned that as a possible scenario... If you have other RB files encrypting in the subfolder[s], then also ensure you use: Sketchup::require(name_without_filetype_suffix) rather than ' load()'... This way the RB files load during testing AND the RBS files still work after the encryption... You have to plan ahead. : Thanks, that should be the only change I need. I was already using encryption but forgot that main.rb was excluded from the encryption on my local copy.