I'm getting 21004 as status value in reply from apple's sandbox server testing auto-renewable subscriptions in ios?
You must replace this text at the top INSERT HERE YOUR ITUNESCONNECT SHARED SECRECT KEY FOR AUTORENEWABLE SUBCRIPTIONS RECEIPT VALIDATION with the secret key that you get from iTunes Connect. (obviously, don't post the full secret on Stack Overflow, though).
The secret is typically a 32 digit, alpha-numeric string that looks something like this 39fkjc38jd02mg72k9cn29dfkm39fk00 (this one is fake).
In (the new) iTunes Connect go to My Apps > (Then click on your app) > In-App Purchases > View or generate a shared secret
go to ituenes connet and then your app and then go to ManageInApp purchases and then here see the left bottom there is an option view or generate a sharedsecret here you can generate an shared secret or you can view the previous shared secret