PayPal Errors Since 1.8.9 Update

[JamesRamos]

I am using PayPal Sandbox API for testing. It was previously working without any issue. However, once the payment now is submitted, I receive a "invalid client_Client Not Authenticated" error. This happens either logged in to PayPal with a sandbox account or using guest checkout. I am able to login and fill out the information, but when I finally submit for payment to process. I get this error.

I have checked and double checked that my Client ID and Secret ID are correct.

The only thing that has changed that I can think of, is I did update the plugin.

I am using the Raphael theme also.

Any suggestions?

 

[JamesRamos]

UPDATE: I have been able to get PayPal sandbox API to work, but only in DEMO MODE. Perhaps I do not fully understand the function of DEMO MODE. Can someone explain this?