I experience the same crash starting with iOS 18.0 (including 18.1.0). Based on this report (https://github.com/apple/swift-foundation/issues/833), something must have changed in the inner workings of Decimal. 0 Foundation <redacted> + 1996 1 Foundation <redacted> + 2432 2 Foundation $sSo9NSDecimala10FoundationE1doiyA2B_ABtFZ + 64