If you are creating archives to be distributed via TestFlight to your beta testers, and you run into this:
…Ouch! What did you do!?!?
Nothing. Xcode is missing a code signing setting. To fix, look at your project Build Settings in the Code Signing section. If Code Signing Resource Rules looks like this:
…then change it to this:
…by simply adding “${SDKROOT}/ResourceRules.plist”. Rebuild your archive, and the issue will be resolved, and TestFlight will create the IPA without complaint.