Delete the associated certificates & keys from your local machine - Mac To get started use Command-Key / Spacebar (opens search) type "keychain". it will bring up keychain access app in list click keychain access app Select the 2nd option [Open Keychain Access] You'll have to supply a password or whatever to get in Look under Certificates tab You'll find a developer certificate for the account. Be very careful you don't delete the wrong one You should be able to delete the associated developer certificates and it will remove the developer account -- the certificate that XCode uses to sign the apps with. You can probably determine which one is which by the associated email address. ie There is one email address tied to each developer account. Good luck

I was moving a large section of a View to a new (child) View and previously i had to refer to an element as self.varname -- however, now this var name was in the parent view and it caused this "generic parameter 'V'" issue. As stated, the best way to get through this is comment out sections of your view. As you do this, you'll see that you'll get more detailed (and more appropriate) errors that will help you find the issue.

I encountered the same error ("Failed to produce diagnostic for expression; please submit a bug report") and then discovered that is related to : passing in a model object that is set with @State the preview code that most likely causes the problem. Here's a simplified example of what I had that caused the problem. struct ParentView: View { @State var userTaskItem: UserTask? // this is my Model I pass into the ChildView var body: some View { Form{ }.sheet(isPresented: $isUserTaskViewShown, onDismiss: didDismiss, content: { ChildView(userTask: $userTaskItem) // passing in bound Model item to child view }) } struct ChildView: View { @Binding var userTask : UserTask? // Model is bound to parent var body: some View { Group{ } } #Preview { // had something like this and I got extremely strange errors. var userTask: UserTask? = UserTask() ChildView(userTask: PreviewHelper.$userTask) } My point is that you need to look closely at your bindings on Models and what your preview is doing.