---
title: "What does VerificationError.invalidEncoding mean in StoreKit 2?"
description: "VerificationResult.VerificationError.invalidEncoding means the signature, certificate chain or another part of a signed StoreKit 2 value uses an invalid encoding. Treat the transaction as untrusted, log the reason and verify it on your server before unlocking."
url: https://revenuedot.app/docs/errors/storekit-verification-error-invalid-encoding
---

# What does VerificationError.invalidEncoding mean in StoreKit 2?

VerificationResult.VerificationError.invalidEncoding means the signature, certificate chain or another part of a signed StoreKit 2 value uses an invalid encoding.

## Quick facts

| | |
|---|---|
| Error | `VerificationResult.VerificationError.invalidEncoding` |
| Where | StoreKit 2, Swift (`VerificationResult`) |
| Available since | iOS 15.0, iPadOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0, visionOS 1.0 |
| What the vendor says | An error that indicates the signature, certificate chain, or other part of value uses invalid encoding. |

## Cause

- StoreKit 2 returns transactions, renewal information and the app transaction wrapped in a `VerificationResult`. It checks them for you, and a value that fails is `.unverified` with the reason as a `VerificationError` ([VerificationResult](https://developer.apple.com/documentation/storekit/verificationresult)).
- Apple's page gives only that definition: a part of the signed value cannot be decoded.
- `invalidEncoding` is one of six reasons Apple lists, next to `invalidSignature`, `invalidCertificateChain`, `invalidDeviceVerification`, `invalidEncoding`, `missingRequiredProperties` and `revokedCertificate`.

## Fix

1. Treat an `.unverified` result as untrusted. Do not unlock content from it and do not call `finish()` on it until you have decided what to do.
2. Do not edit, re-encode or store the signed JWS text through code that changes it. Keep `jwsRepresentation` byte for byte.
3. Log the `VerificationError` and the transaction ID, then check the same transaction on your server with Apple's App Store Server Library or the App Store Server API.
4. If it only happens in testing, check the test environment (Xcode StoreKit configuration, sandbox account) before changing code.

## Example

```swift
import StoreKit

// Only a verified transaction may unlock content. Log the reason when a transaction is unverified.
func handle(_ result: VerificationResult<Transaction>) {
    switch result {
    case .verified(let transaction):
        print("Unlock \(transaction.productID)")
    case .unverified(let transaction, let error):
        if case .invalidEncoding = error {
            print("The signed value has an invalid encoding for \(transaction.productID); do not unlock")
        } else {
            print("Verification failed: \(error)")
        }
    }
}
```

*Compile-checked: `npm run check:snippets` type-checks this snippet with `swiftc` against the Apple SDK (macOS target, checked 2026-10-03).*

## How the RevenueDot SDK reports it

The RevenueDot `purchases-ios` fork turns an unverified transaction from a purchase or a transaction update into `ErrorCode.storeProblemError` (code 2) with the `VerificationError` as the underlying error, and it does not unlock the purchase. When it only reads existing transactions (offline entitlements, transaction history), it logs a warning and skips the unverified ones.

## Related

- [What does VerificationError.invalidSignature mean in StoreKit 2?](https://revenuedot.app/docs/errors/storekit-verification-error-invalid-signature.md)
- [What does storeProblemError (code 2) mean in the purchases SDK?](https://revenuedot.app/docs/errors/sdk-store-problem-error.md)
- [What does invalidReceiptError (code 8) mean in the purchases SDK?](https://revenuedot.app/docs/errors/sdk-invalid-receipt-error.md)

## Source

- [Apple: VerificationResult.VerificationError.invalidEncoding](https://developer.apple.com/documentation/storekit/verificationresult/verificationerror/invalidencoding)
- [Apple: VerificationResult](https://developer.apple.com/documentation/storekit/verificationresult)
- [RevenueDot purchases-ios: StoreKit2TransactionListener.swift](https://github.com/revenuedot/purchases-ios/blob/revenuedot/main-patches/Sources/Purchasing/StoreKit2/StoreKit2TransactionListener.swift)

Checked: 2026-10-03