I'm seeing the same thing here. "[API] cannot add handler to 3 from 3 - dropping" filling my logs on a Mac Catalyst app build tin SwiftUI. Even with something like var body: some View { List(list, id: \.id, selection: selection) { project in text(verbatim: project.name) } } I'm seeing it appear when the list appears. Add in some swipeActions, contextMenu and a whole lot more will appear.

I'm getting this too. No idea how to solve it.

Bump. Same here. Looking for a solution. In my case I have a local server in the test framework for UI testing.

BUMP - Anyone else seen this? I've since found some people with the same error, but for what appears to be different reasons.

I have the same problem. However you don't have to re-download Xcode to get the extensions back. Just drag Xcode from the Applications folder to somewhere else. Desktop is fine. Then drag it back. The act of adding Xcode to the Applications folder (again) triggers whatever it is in OS X that reads the extensions.