I have iOS 27 and was renovating my bathroom when I decided to develop a few apps for the App Store. Unfortunately, the app has too many bugs and crashes on various devices, so I had to remove it from the App Store. How can I fix this problem? I was using iOS 27 on an iPhone 17 Air and iOS 15 on an iPhone 6s.

I developed an app for the first time today and bought an iPhone 6s in 2015. The problem is that the app compatibility isn't optimal.I receive error messages when compatibility is set to iOS 6 and higher.