Incredibly, this is still an issue with iOS 14.3 released version and the latest version of Xcode. Submitting bug reports has just gotten the response to add sysdiagnose over and over, even thought it literally happens 100% of the time with absolutely any project if you're trying to rotate a phone running iOS 14 attached to the Xcode debugger. I haven't tried the iOS 14.4 beta, does anyone know if it's still broken there?

I had the same problem, and the only solution I could find was: Pair watch with a device running iOS 13—either another test device, which I had thankfully, or revert your current device and start from there) Install the watchOS 7 beta profile to the watch—the order of this step is important, the watch won't be able to update to 7 but you need the profile on there, I think that's what's causing the problem Make sure watchOS has restarted and the profile is actually installed on the watch Update the paired device to iOS 14 beta Update the watch to watchOS 7 beta If you downgraded your main device for this, you can end here, otherwise unpair the watch and re-pair it to your main device I've filed a bug report about this. If it's not possible to add a new watch to an iOS 14 Beta device, it should be in the release notes.