I encountered exactly the same error when I try to fetch images in an NSCollectionView using PhotoKIt.I implemented a MTKView (Metal Kit View) on the same window so that I can make a real time monitorof CIFilter effect.Without that MTKView, there was no trouble in fetching images. So I am guessing that there is some conflictbetween PhotoKit+NSCollectionView and MTKView.Sorry I am not giving you answers to your question but I just want let you know that you are not the only onewho is in trouble.

It turned out that the error occurred only in the XCode simulator but disappeared on the real Application. The App never crash although the NSCollectionView stops smooth scroll occasionally but it's acceptable.

You were right. NSCollectionView only repeated the fetch command to PhotoKit so many times and it has essentially nothing to do with this crash.By the way, I am wokring on macOS project not iOS. What I meant by "in the simulator" was the App launched inside the XCode by 'Run' command where I encountered the error. However, when I actually built a stand alone application using 'Archive' command, that applicataion worked without the crash. Did you try that ?