Hi,
This happened to me in the exact situation what GeekyChick described above. I wanted to remove the Main storyboard from the Info.plist alongside deleting the Main.storyboard file as well. If this is the case, you have to remove the "keys" from this Info property list: Application SceneManifest/Scene Configuration/Application Session Role/ Item0/ Storyboard Name
Main storyboard file base name
(As I mentioned you have to remove these keys, not just the Main.storyboard value.
With this the error should go away.