receiptAlreadyInUseError (error code 7): Receipt already in use

• The backend answered 7102 (cannot transfer purchase), and the SDK maps it to receiptAlreadyInUseError (BackendErrorCode.swift, errors.kt).
• A customer restored or re-posted a store purchase while signed in as a different app user than the one who bought it.
• The project's restore behavior forbids moving the purchase. RevenueCat documents the options in its restore behavior docs.
• A shared device or a reinstall with a new app user ID after logging out, so the old account still owns the purchase.

• Do not retry. The same request fails the same way until the setting or the account changes.
• Tell the customer the purchase is linked to another account and show how to sign in with it. Do not say whose account it is.
• Do not grant access from the error. Grant it only when customer info shows the entitlement active.
• Log it with the app user ID, because a spike usually means shared devices or a missing login step.

// Swift
do {
  let result = try await Purchases.shared.purchase(package: package)
} catch let error as ErrorCode where error == .receiptAlreadyInUseError {
  // handle receipt already in use
}

// Kotlin
if (error.code == PurchasesErrorCode.ReceiptAlreadyInUseError) { /* ... */ }

On RevenueDot: On POST /v1/receipts, RevenueDot answers HTTP 400 with code 7102 when another known user owns the purchase and the project's transfer_behavior is keep, or transfer_if_no_active while the owner still has an active subscription. The default transfer moves the purchase and sends a TRANSFER webhook. An anonymous owner is always merged into the user who restores. Sandbox purchases can use sandbox_transfer_behavior instead.