ios - error: Unable to resolve build file: XCBCore.BuildFile

Question

error: Unable to resolve build file: XCBCore.BuildFile (missingTargetProductReference("3bf83096e50de72a94699e9afc1133ebe3512682230d04680075c283a974e273")) (in target 'MyTarget')

Xcode 10 is giving this error immediately when trying to build our project. It's not immediately clear what is causing it.

How can I resolve it?

Answer 1

For XCode 10 Beta: Problem occurs when I have two workspaces open that share the same project directories. Solution was

Short version

1. Shut down all but one workspaces
2. exit XCode and reopen XCode
3. XCode > Product > Clean Build Folder

Longer version

1. Shut down all but one workspace
2. XCode > Preferences > Locations > Derived Data > goto directory ~/Library/Developer/Xcode/DerivedData
3. Clear out subdirectories from DerivedData
4. exit XCode and reopen XCode
5. XCode > Product > Clean Build Folder

Thanks to @aferriss answer for the clue.