This is something I've been struggling with for some time. The hierarchy of my app makes this harder to diagnose. But like you, it was working fine for years. In my case, this app supported three column-layouts prior to the release of column-based split views. In order to do so, we have a concept of a NestedSplitViewController -- which is a UIViewController that owns a UISplitView. We're running into the same issue with Xcode 15 – and can't seem to pin it down.

I run into this every time I swap branches and my xcodeproj file changes in one way or another. I have to Resolve Package Dependencies manually every time.

Seems like there's a simple fix to this: Add an environment variable for the missing fallback directory. For example: DYLD_FALLBACK_LIBRARY_PATH=/Library/Developer/CoreSimulator/Volumes/iOS_22F77/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.5.simruntime/Contents/Resources/RuntimeRoot/System/Cryptexes/OS/usr/lib/swift The same as the above would apply to a different simulator combo.