SwiftUI Preview error (process launch failed)

Question

It seems that somehow i am screwing the SwiftUI Preview. When loading the simplest Preview like

struct MaterialView_Previews: PreviewProvider {
    static var previews: some View {
        Text("Hello, World!")
    }
}

it crashes with following error:

RemoteHumanReadableError: The operation couldn’t be completed. Transaction failed. Process failed to launch successfully. (process launch failed)

BSTransactionError (1):
==transaction: <FBApplicationProcessLaunchTransaction: 0x6000012e01c0>
==error-description: Process failed to launch successfully.
==error-reason: process launch failed
==NSLocalizedFailureReason: Transaction failed. Process failed to launch successfully. (process launch failed)

I can't figure out what causes this issue since i can run my app in the simulator w/o any errors. I use XCode 12 Beta 4. Any ideas?

Answer 1

I had a similar issue, but in my case diagnostics showed: RemoteHumanReadableError

My fix was to quit Xcode (close window and quit from the menu or use CMD+Q).

Delete contents of:

~/Library/Developer/Xcode/DerivedData/