Every payment returning to cancel URL and PAYMENT_ALREADY_DONE (sandbox)

[atkulp]

I'm uploading a cart of one or more items for payment.  After paying, the user sees "Your payment was completed.  To continue shopping, please return to the merchant" with the "Return to Merchant" button.   Upon clicking, the user is taken to the cancel_return URL rather than the return URL.  This worked last year (it's a site for an annual event).  This is in Sandbox.  I'm afraid to try it in production while this is happening.

Form payload:

cmd: _cart
upload: 1
no_shipping: 1
currency_code: USD
business: [business email]
item_name_1: Item Name
item_number_1: 3ac53ba1-7fe6-43e6-b06a-407566896faa
amount_1: 50
shopping_url: https://site.com/checkout?source=paypal
return: https://site.com/checkout?source=paypal&a=paid
cancel_return: https://site.com/checkout?source=paypal&a=cancel

Response:

After successfully clicking the payment button, the user is directed to the completion page

I noticed that the actual URL at the moment reflects an error:

https://www.sandbox.paypal.com/webapps/hermes?token={TOKEN}&useraction=commit&rm=2&mfid={IDENTIFIER}.../checkout/genericError?code=PAYMENT_ALREADY_DONE

Upon clicking the button, they are taken to my "cancel_return" URL.  If I look at the business transactions, it reflects a successful payment, and my IPN endpoint correctly receives and records the payment details.  What's happening here?

[Druid-77]

I have the same problem.

[developer_cts]

I am facing the same issue.

[dany0]

Same here, it redirects to cancel_return url

[atkulp]

Can we get a response from PayPal?  This is clearly not one-off.  That said, I've tested my code on production and it works as expected.  It's just an issue with sandbox.

[developer_cts]

I am getting the issue with both production and sandbox mode. Please guide how to fix this.

[Druid-77]

Yes, my production and sandbox mode doesn't work too

[thief2]

I am getting the same issue.

For me this is when using sandbox for testing purposes.

[Strateges]

Same problem here with a WooCommerce.

[rams007]

same things happens to me