The exact same problem is also triggered through SwiftUI's ColorPicker(), when supportsOpacity is set to false. As with the original post, the issue is with macOS 26.0 and Xcode 26.0.1 when building a macOS app.

I was having the same (or similar) problem: crashing when more than one tab opens, resulting in the same error described in this discussion. The problem does seem to be related to a bug when the toolbar method is called on the NavigationSplitView view. I also found that the problem does not occur when toolbar is called on a subview within NavigationSplitView. In attempting to resolve this, I found that the problem also only occurs when the toolbar method is provided with a specific id parameter (i.e.: toolbar(id: "toolbar"){...}). If an id is not provided, I don't get an error. Hopefully this helps narrow-down and isolate the specific cause of the problem.

Having exactly the same problem since updating to Sonoma 14.2 with Xcode 15. Like buster6060 observed, it affects macOS-targeted projects that use TextField.

The problem appears to have been fixed with macOS 14.0, iOS 17.0, and iPadOS 17.0. To the unsung hero at Apple, who took the time to fix this, thank you!

I had the same (or similar) problem in trying to build a simple app that uses AppIntents to create an App Shortcut -- the same error appearing when running the App Shortcut in macOS. I was using Xcode 14.3 on macOS 13.4. Setting aside the problem, I upgraded to macOS 13.5 (Xcode remaining at 14.3) and now, strangely enough, the App Shortcut began working as expected. I was building a Multiplatform app and the error never appeared when running in iOS.

MagnificationGesture has now been deprecated: MagnificationGesture

There's a recent question (asked Nov 1) posted on Stack Overflow, sharing the same problem: How to set PDFPageOverlayViewProvider for PDFView? I'm also having difficulty getting pageOverlayViewProvider to work properly, albeit with NSViewRepresentable.