Okay I have think cause of that : UNCAUGHT EXCEPTION (NSInvalidArgumentException): -[__NSCFBoolean mutableCopyWithZone:]: unrecognized selector sent This says that the selector provided for mutableCopyWithZone is not known. because usually this is the system call: I believe your problem is that you deleted your Xcode 12 incorrectly. or haven’t At all. try deleting your Xcode 12 with some sort of app uninstaller . That should work

I think this could help you. https://developer.apple.com/forums/thread/667088

Well registrating a cell only when you need it seems like a bad practice. I don't know how many different cell types you have on the same collection view but I would suggest registrating all needed cells in viewDidLoad() method seems like when you are using the same cell again it registers again but its already registered so it crashes your app. If you can't provide registrating all cells at once -> decompose your collection view to maybe different types of needs and depending on that need register cells you require. If your cells registeration requires collectionView data - its bad practice

New Build System

Okay I'm not sure but if there's a stackTrace you could provide that would be great. I'm seeing that your error is SIGBUS, KERN_PROTECTION_FAILURE with message: (Data Abort) byte write Permission fault Usually that means that you are trying to execute or use a region of memory that is read only. Seems like its too deep to dive in I hope your can solve your issue reading this https://developer.apple.com/documentation/xcode/investigating-memory-access-crashes (search for: KERN_PROTECTION_FAILURE)

Hey! I'm not sure if I know how to fix your problem but I know that SF Symbols refers to icons that already are in Xcode. You can use your bug.fill image without even importing it to the project Try let image = UIImage(systemName: "bug.fill")