Can't purchase IAP (sandbox) on iOS 8 beta

Question

I'm updating an app with IAP to iOS 8, but I can't test any IAP functionality. Attempting to purchase any IAP (both consumable and non-consumable) as a test user gives me a failed transaction with the (non-helpful) error:

Error Domain=com.apple.accounts 
Code=18 "The operation couldn’t be completed. (com.apple.accounts error 18.)"

I'm using MKStoreKit, but I'm pretty sure the problem isn't in there -- the transactions look good before being sent, and fail silently when sent. And this worked fine before I started the update.

Where else can I look to try and debug this?

Answer 1

I had to sign out of my itunes account on my ipad and then it allowed me to download an app. I had this same error message before I did this, so it may help you.