Thanks very much for the advice!

I've temporarily worked around this issue by adding an ObjC extension to NSProxy: @interface NSProxy (Plane) -(id) plane; @end @implementation NSProxy (Plane) -(id) plane { return nil; } @end which allows the app to continue initializing as normal. While breakpointing in that shim code, I also found the suspect caller in the breakpoint: I'm not quite sure what MRUIPlacementTargetFromAnchoringTarget is, and also, I do not currently have any anchors in my RealityView scene, so I suspect there might be some expectation that my older code is not meeting? Hopefully if this is a new expectation, that future exceptions might be a bit more self explanatory about what is required on behalf of the application.

Thanks for confirmation.