By bypassing the sandbox page and going directly to the production page, I managed to get four of our six ZenCart sites to accept the application IDs and access tokens, though I kept having to experiment with the access tokens on the credentials page and the OAuth page. Some sites accepted one code, and the other sites insisted on using the other code.

I'm still having problems with two of the sites, though. One of them (www.timelesserotica.com) won't accept either access token, and when I click the button to authorize the account, it gives me an error message that says the page isn't working; it's currently unable to handle this request; http error 500.

The sixth site (www.alanachurch.com) is even more baffling. I've uploaded the square_handler.php file and the new' includes' folder multiple times and verified that they're there in the right place, but ZenCart's payment modules page refuses to show Square as a payment option.

Added to that, none of the sites will actually process a transaction. When I get to the Payment Information page, it highlights the Credit Card option, but all the fill-in fields are missing (card number, cvv number, expiry date, and postal code). www.book-oasis.com is a perfect example. I selected a book, logged in, and tried to purchase the book using a real credit card. I can't because the credit card fields are missing.

Square flatly refuses to help, and said I had to talk to you. Can someone please help me?? We're rather desperate to change these sites away from Paypal, and need to get your Square module up and running asap. Thank you!