invalidPromotionalOfferError (error code 34): Invalid promotional offer

• StoreKit 1: invalidSignature (the signature in a payment discount is not valid), invalidOfferIdentifier (the identifier cannot be found or is not active), invalidOfferPrice (the price set in App Store Connect is no longer valid) and missingOfferParams (source).
• StoreKit 2: Product.PurchaseError cases invalidOfferSignature, invalidOfferIdentifier, invalidOfferPrice and missingOfferParameters.
• The signed data the SDK received from the backend was unusable, so the SDK builds this error from it (PurchasesOrchestrator.swift).
• A signature made with the wrong key, or for a different app user ID than the one buying, can be refused as invalid.
• The offer was edited or turned off in App Store Connect after the signature was made.

• Do not retry the same offer. A bad signature or identifier fails again.
• Fall back to the regular price, and alert yourself. This is a setup problem.
• Do not grant access, and do not apply the discount yourself.

// Swift
do {
  let result = try await Purchases.shared.purchase(package: package)
} catch let error as ErrorCode where error == .invalidPromotionalOfferError {
  // handle invalid promotional offer
}

On RevenueDot: POST /v1/offers signs each requested offer with the app's In-App Purchase key and the app user's account token. With no key it answers 400 with code 7234 and fails only that offer. The server cannot check an offer against Apple, so Apple's rejection shows up on the device as this error.