It looks like this was resolved in macOS Sequoia Developer Beta 4.

It certainly looks like I shouldn't be receiving the prompt based on this sentence from the change notes. Specifically, the app must use FileManager to get the app group container path and meet one of the following requirements: the app is deployed through Mac App Store; the app group identifier is prefixed with the app’s Team ID; or the app group identifier is authorised by a provisioning profile embedded within the app The second criteria doesn't look like it is being honored. Another project impacted by this is NetNewsWire. Although it isn't a Mac Catalyst app, it uses an App Group suffixed with group. (I didn't realize macOS differed from iOS when I contributed the code to NNW.) Based on the change notes, it shouldn't be impacted either, but it does receive the prompt.

There is a sample project included in FB14171101 which I filed about the issue. Here is the code in the sample project which triggers the issue. let appGroup = "group.io.vincode.AppGroupSampleProject" let containerURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: appGroup) let testFileURL = containerURL!.appendingPathComponent("test.txt") let fileData = "Sample file data".data(using: .utf8) try? fileData?.write(to: testFileURL) The alert appears when writing to the file. Zavala is an Open Source project if you want to look at it in particular. I'm sure several other projects have to be getting tripped up by this. If you are building a Mac Catalyst project, Xcode prompts you to create your App Group beginning with group. Xcode doesn't even allow you to have a different App Groups for iOS vs. macOS in the same target. It certainly feels like App Groups starting with group should be allowed.

Yes. My app Zavala is impacted by the macOS 15 changes.

I have almost the same issue. It looks like in Sequoia, you no longer can start your group folder name with group. You have to use your team identifier instead to avoid the dialog you are getting. Hopefully this is something that gets corrected in future betas as I think it is going to impact a fair number of apps. The RSS reader Unread was also hit with this change. You can read about it on the Golden Hill Software blog.