hi!
Most likely cause of this is that Paid Memberships Pro does not specifically integrate with the 2Checkout sandbox environment. Easy way to tell is if the page that you are seeing the PE102 error on is “www.2checkout.com/checkout/purchase” and not “sandbox.2checkout.com/checkout/purchase”.
Attempting to use a sandbox account in a production environment will result in a PE102 error message.
Based on the woocommerce instructions here: the “Approved URL” in your 2Checkout account should be set to http://yourdomain.com/?wc-api=WC_Gateway_Twocheckout . I would recommend changing this, and attempting to place a test sale again.
