Worked it out.

Although the update log indicates that Xcode 26 has the lowest support level of iOS 15, historical versions can still enable device debugging by adding the corresponding platform's DeviceSupport (Developer Disk Image). I haven't found any restrictions for iOS 12. If anyone knows the solution, please do let me know. Thank you very much for your assistance. ZQ Han. Thanks!

Hi, has this problem been resolved? I've encountered the same issue with debugging on iPhone 6P(iOS12.4.4), but the error messages aren't exactly the same. https://developer.apple.com/forums/thread/817661