In-app purchases made via promo codes return empty developer payload string

Question

I have an app published to the alpha channel, with an in-app (un)managed item that costs $1.

When I purchase normally, i.e, use a credit/debit card Google returns the correct developer payload string, but if I choose to "redeem" a promo code and enter said code, Google returns an empty developer payload string, and thus authentication fails in 'onIabPurchaseFinished()'.

I should mention that this only occurs if I choose to redeem a code from the app's purchase flow, and everything works flawlessly if I open Play Store first, redeem the code, and then come back and open the app.

Is this a bug on Google's part?

EDIT: The Play Store thing is expected, since it can't know your payload and the purchase is done without having to check for it.

Uhhuh

If I use the code from play store and then I open my app, I've got an empty string. It's obvious why, however it's really a big hole. – Curd

I have the same issue so I can't validate purchases done with promo code :( – Wrapper

Same issue and got the same problem while querying purchases. I tried to contact google support via support.google.com/googleplay/android-developer/contact/…. Waiting an answer... – Intracellular

Also faced with the same issue – Andrews

Update: further investigations in progress by Google team. – Intracellular

@JérémyReynaud If the code is used inside the play store app, your app is not involved at all in the process, so it's normal that you won't receive any developer payload, play store can't know your string. – Curd

@Curd you're completely right. As you note in your first comment it is a big hole as the only solution for now will be to avoid checking developer payload in the getPurchases() result as we don't know if the purchase has been made "normally" or with a promotion? Google may provide a way to declare our developer payload in the developer console to cover this case, don't you think? – Intracellular

Update: answer from Google: "Our team has looked into the behavior you reported and identified there is no bug existed. In this case, the recommendation for you is to review the whole loop of API setup and coding to ensure it works properly. Our team is trained to provide technical support for app development questions, so I'm unable to provide you further assistance on this issue." I try to ask for more information than "there is no bug"... – Intracellular

This is the discussion in the Google support group: groups.google.com/d/topic/android-developers/bDiYGoL-qBs/… – Cowes

For information, an issue has been opened on the android-play-billing project on GitHub: github.com/googlesamples/android-play-billing/issues/7 – Intracellular

Anyone figure out this issue yet? – Impair

Any update on this issue? – Zenobia

When we all are waiting for Google response - do you have any temporary solution for this problem? I don't see any possibility to check that payment was done with credit card or promo code... Do you bypass payload check for this moment? – Scotfree

I had a similar problem. I ended up uninstalling the app, and then redeeming the promo code, and the app now recognizes it. it's a temporary fix, but it works @Scotfree . – Wertz

Do you have the app published (without inapp purchase) normally (not alpha/beta)? There seems to be issues, if you dont. Dont ask me, where I read this .. – Guardsman

Seems you can refer to this : #18614020 – Contagion

Answer 1

This issue was opened on the google's android-play-billing samples repo. Looks like it was ignored for a long time and was eventually closed with this comment. In short, they have following suggestions.

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We reviewed our guidelines and internal APIs, and since the developerPayload is not supported across all features on In-App Billing API (including promocodes), we are removing the recommendation to use it as a security check.

As you can see in our documentation, on the page Implementing In-app Billing (https://developer.android.com/google/play/billing/billing_integrate.html) we've added a recommendation:

Caution: Don't use the developerPayload field for security validation purposes. This field isn't always available when completing tasks related to In-app Billing. For more information about security best practices, see the In-app Billing Security and Design guide.

Our recommendation is to validate on your own backend, using the Play Developer API.

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Stationer

Thanks for the info, we have to use an "optString" method to return as a fallback value an empty string "" : p.setPayload(data.optString("developerPayload")); – Restrictive