iOS app won't run on device any more under iOS 12: Unrecoverable CT signature issue

Question

I have an app that crashes immediately when starting under iOS 12 on a device.

The console shows the following error:

kernel AMFI: \'AppNa

Answer 1

I'm not sure if this will fix it for everyone, but I had the exact same problem and it solved the problem for me. In Keychain Access, I set the trust settings to "Use System Defaults" for the following certificates:

• Apple Worldwide Developer Relations Certification Authority
• Developer ID Certification Authority
• iPhone Developer: {email}
• iOS Distribution

Some of them were set to "Always Trust" before, and changing it seemed to resolve the issue. When running Xcode however, it initially still did not work, so I cleaned the build and restarted Xcode, and the application finally launched.