Same issue. I don't even have Mac support, iPhone only.

I was struggling with this error for a whole day, what helped me at the end: 1 - Deleting all spm cache and derived data: rm -rf ~/Library/Caches/org.swift.swiftpm ~/Library/Developer/Xcode/DerivedData ~/Library/org.swift.swiftpm ~/.swiftpm/xcode/ 2 - Adding package with "Add Anyway" option 3 - Fully closing Xcode (cmd + q) and running this in project folder: xcodebuild -resolvePackageDependencies -disablePackageRepositoryCache Hope it helps someone! :)

I have it too. MacOS Sequoia Public Beta + Xcode 16 Beta 3. "Frameworks, Libraries, and Embedded Content" in General project tab doesn't return any results, I need to manually re-add dependency to activate it in other menu.

Same error. MacOS Sequoia Public Beta + Xcode 16 Beta 3. Every preview crashes after some time and doesn't recover until I close and reopen Xcode.

I had same issue, but when trying to run tests. In my case the error was lying in my Package.swift file. I forgot to import a library for a target there and Xcode didn't show me corresponding error, when I fixed that, this error went away.

Same issue. Xcode 15.3. Every second build is failing. Configuration doesn't matter, all of my projects, simulator/device, iOS 16/17.

Still an issue with Xcode 15 & Swift 5.9! Non-async version gives a useless warning and async version crashes the app with :0: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value in case where function doesn't return anything. Any hope for a fix?