I use Unity 2019.4.11f1
Create new project, and switch to Android platform.
Enable Service In-app purchase
Import Unity IAP Store package 2.0.0 and install.
Create the Tangle files from Window/Unity IAP/Receipt Obfuscation Validator.
And
Scripting define symbols add RECEIPT_VALIDATION
Build error and show error log:
Assets\Plugins\UnityPurchasing\script\IAPDemo.cs(471,48): error CS0103: The name 'GooglePlayTangle' does not exist in the current context
Assets\Plugins\UnityPurchasing\script\IAPDemo.cs(471,73): error CS0103: The name 'AppleTangle' does not exist in the current context
Thank you very much for your reply my friend.but problem solved.The problem was related to IN-app purchasing, I deleted it and reinstalled it.The problem is solved. I guess there was a problem with the first installation.