Same thing happened to me. The hint in the error log was about app signing. I had just renamed my app and one of the residuals was that the Xcode set the app to be signed locally instead of "Developer". The app signing was set to "Developer" before the app rename, so I don't know why Xcode set that to a different value. Setting it back to "Developer" fixed the problem for me.

Thanks for your reply. In doing more reading, I see that you were posting in a thread about TPInAppReceipt which I just found and will try later today. There are two reasons why I wanted to avoid using OpenSSL: It's like using a hammer to push in a thumbtack. I didn't know if using OpenSSL would open up a can of worms for encryption compliance. I'm just trying to validate receipts with as little headache as possible. My app has been finished for two weeks but I'm stuck with trying to properly fix this IAP issue.

Thanks, I'll take a look at StoreKit 2 more closely.

I just wanted to mention that after looking at StoreKit 2 more closely, it did exactly what I needed. I moved from SK to SK2 in about two hours...maybe less. Thanks for the heads up on that.