Full error for googleplay item purchases here:
NullReferenceException: Object reference not set to an instance of an object
AndroidIAPExample.ProcessPurchase (UnityEngine.Purchasing.PurchaseEventArgs purchaseEvent) (at Assets/Scripts/AndroidIAPExample.cs:349)
UnityEngine.Purchasing.StoreListenerProxy.ProcessPurchase (UnityEngine.Purchasing.PurchaseEventArgs e) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Purchasing/StoreListenerProxy.cs:34)
UnityEngine.Purchasing.PurchasingManager.ProcessPurchaseIfNew (UnityEngine.Purchasing.Product product) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Purchasing/PurchasingManager.cs:311)
UnityEngine.Purchasing.PurchasingManager.OnPurchaseSucceeded (System.String id, System.String receipt, System.String transactionId) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Purchasing/PurchasingManager.cs:128)
UnityEngine.Purchasing.JSONStore.OnPurchaseSucceeded (System.String id, System.String receipt, System.String transactionID) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Stores/BaseStore/JSONStore.cs:168)
UnityEngine.Purchasing.FakeStore.<>n__0 (System.String id, System.String receipt, System.String transactionID) (at <52872485de1c4ad9a6ba8021e4a1c4fe>:0)
UnityEngine.Purchasing.FakeStore+<>c__DisplayClass15_0.<FakePurchase>g__handleAllowPurchase|0 (System.Boolean allow, UnityEngine.Purchasing.PurchaseFailureReason failureReason) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Stores/FakeStore/FakeStore.cs:142)
UnityEngine.Purchasing.FakeStore.FakePurchase (UnityEngine.Purchasing.ProductDefinition product, System.String developerPayload) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Stores/FakeStore/FakeStore.cs:161)
UnityEngine.Purchasing.FakeStore.Purchase (System.String productJSON, System.String developerPayload) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Stores/FakeStore/FakeStore.cs:126)
UnityEngine.Purchasing.JSONStore.Purchase (UnityEngine.Purchasing.ProductDefinition product, System.String developerPayload) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Stores/BaseStore/JSONStore.cs:143)
UnityEngine.Purchasing.PurchasingManager.InitiatePurchase (UnityEngine.Purchasing.Product product, System.String developerPayload) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Purchasing/PurchasingManager.cs:69)
UnityEngine.Purchasing.PurchasingManager.InitiatePurchase (System.String purchasableId, System.String developerPayload) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Purchasing/PurchasingManager.cs:80)
UnityEngine.Purchasing.PurchasingManager.InitiatePurchase (System.String productId) (at ./Library/PackageCache/com.unity.purchasing@4.10.0/Runtime/Purchasing/PurchasingManager.cs:49)
AndroidIAPExample.BuyProductByID (System.String productID) (at Assets/Scripts/AndroidIAPExample.cs:95)
AndroidIAPExample+<>c__DisplayClass18_0.<OnGUI>b__0 () (at Assets/Scripts/AndroidIAPExample.cs:247)
UnityEngine.Events.InvokableCall.Invoke () (at <c2d036c16ca64e0eb93703a3b13e733a>:0)
UnityEngine.Events.UnityEvent.Invoke () (at <c2d036c16ca64e0eb93703a3b13e733a>:0)
UnityEngine.UI.Button.Press () (at ./Library/PackageCache/com.unity.ugui@1.0.0/Runtime/UI/Core/Button.cs:70)
UnityEngine.UI.Button.OnPointerClick (UnityEngine.EventSystems.PointerEventData eventData) (at ./Library/PackageCache/com.unity.ugui@1.0.0/Runtime/UI/Core/Button.cs:114)
UnityEngine.EventSystems.ExecuteEvents.Execute (UnityEngine.EventSystems.IPointerClickHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at ./Library/PackageCache/com.unity.ugui@1.0.0/Runtime/EventSystem/ExecuteEvents.cs:57)
UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction`1[T1] functor) (at ./Library/PackageCache/com.unity.ugui@1.0.0/Runtime/EventSystem/ExecuteEvents.cs:272)
UnityEngine.EventSystems.EventSystem:Update() (at ./Library/PackageCache/com.unity.ugui@1.0.0/Runtime/EventSystem/EventSystem.cs:530)
Validation failed: /Inventory/RedeemGooglePlayInventoryItems: Internal server error
UnityEngine.Debug:Log (object)
AndroidIAPExample/<>c:<ProcessPurchase>b__26_1 (PlayFab.PlayFabError) (at Assets/Scripts/AndroidIAPExample.cs:348)
PlayFab.Internal.PlayFabUnityHttp:OnResponse (string,PlayFab.Internal.CallRequestContainer) (at Assets/PlayFabSDK/Shared/Internal/PlayFabHttp/PlayFabUnityHttp.cs:220)
PlayFab.Internal.PlayFabUnityHttp/<Post>d__12:MoveNext () (at Assets/PlayFabSDK/Shared/Internal/PlayFabHttp/PlayFabUnityHttp.cs:159)
UnityEngine.SetupCoroutine:InvokeMoveNext (System.Collections.IEnumerator,intptr)