I'm a webmaster for a small business trying to use a 3rd-party payment widget on my website, and I inserted the API username, API password, and API signature that I generated from employer's business account.
Previously I had tried using a sandbox business account to test the widget, but the widget failed to proceed to the PayPal redirect stage. I contacted the maker of the widget, who helped me understand that sandbox credentials would never work in this widget, because it's not using the sandbox environment.
So, I created an extremely inexpensive product to try testing the widget by purchasing with my personal PayPal account. Sure enough, after replacing the sandbox API credentials with the valid credentials generated by my employer's business account, I was able to proceed with the test payment all the way through to the PayPal redirect. I signed in with my personal PayPal account and submitted the payment normally, just as I do when I buy real products with PayPal.
Then the PayPal checkout redirected back to the homepage of my website, with the string "?payment_error=1" appended to the URL. The payment is not recorded in my Activity log.
I suspect this might be an IP address problem.
The widget is currently configured with the local address of my development version of the website inside my XAMP environment. This is set up correctly, because the redirect correctly leads to the development version's homepage, not the live version's homepage. However, I'm wondering if PayPal has some way to detect that this version of the website is running locally (even though in a webserver environment), and is disallowing the transaction for that reason.
