Similar issue, solved by unpairing my old watch and connecting Xcode and toggling developer mode on the watch directly

I did find a workaround for this, simply wrap your Data object in a Codable struct, like this... struct DrawingData: Codable { var data: Data init(data: Data) { self.data = data } } When you initialize the Model class, make sure to call an init with drawingData (or whatever variable type, as long as it's a codable struct) that is of type DrawingData (or whatever you rename this to). Prior to wrapping the Data object, I had the same crash you all are reporting. I also filed feedback :)

I also am having this issue however, it appears to go away once I removed roomSession.stop() that was being called before the session started