SKPaymentTransactionStateFailed, but no error property returned?

Hi. We have an app with IAP coin purchases. We've recently received mail from one of our users, saying he couldn't purchase any coins. I looked at his session logs and saw 3 Failed IAP events, but no fail reason logged. Here's the related code:

- (void)_purchaseRequestFailed:(SKPaymentTransaction *)transaction state:(StoreTransactionState)state error:(NSError *)error

{

IAPProduct *product = [self getProductWithId:transaction.payment.productIdentifier];

if (error.code==SKErrorPaymentCancelled) {

[_metricsManager logFailIAP:product failReason:@"Payment canceled"];

} else {

[_metricsManager logFailIAP:product failReason:error.localizedDescription];

}

if ([_delegate respondsToSelector:@selector(didSucceedPurchasingProduct:)]) {

[_delegatedidFailPurchasingProduct:product];

}

}

---- inside logFailIAP:

if (failReason != nil && failReason.length > 0) {

[metricsDictionary setObject:failReason forKey:MetricsEventParameterFailReason];

}

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My question is: is there any case where, you get "SKPaymentTransactionStateFailed" but, have an empty error.localizedDescription? My guess is, this is caused by a faulty internet connection, but I can't be sure, because Apple does not list the possible errors.