My XCode 15 is also crashing on the same validation step but this is a Mac App rather than ios. The app is one I've updated and validated many times before but this is the first time I've attempted it with XCode 15 and Sonoma.

I had the same issue - "provisioning profile does not contain the signing certificate" - and the above info led to the solution: I was busy exporting the existing certificates to .p12 when I noticed one had expired. Deleting that one from the key chain did the trick - the app then validated correctly with auto signing, finding the right certificates on its own.