You can copy the device support from a newer version of Xcode to an older version, even if it does not run on your OSX version. Download the new Xcode > right click on it > show package contents > Contents > Developer > Platforms > iPhoneOS.platform > DeviceSupport, copy the versions you want from here (e.g. 10.3) to the same folder in the Xcode version that your OSX supports. After you open the new Xcode and connect your device it will process the symbols which can take a while, but after it's done you can debug apps again.