Difference Between China's Country Codes CN and C2 #country_code

The difference between PayPal's CN and C2 country codes for China, and how to use each in cross-border e-commerce.

PayPal Does Not Have a Function to Block Specific Accounts

PayPal has no built-in account block list, so I note how to implement one on the merchant side with SetExpressCheckout and GetTransactionDetails APIs.

PayPal RefundTransaction API cannot refund after 180 days from payment date

The PayPal RefundTransaction API cannot refund after 180 days — notes on workarounds with MassPay and DoNonReferencedCredit APIs.

[PayPal] TOKEN Valid Time is 3 Hours by Default, Maximum 72 Hours

The PayPal SetExpressCheckout TOKEN is valid for 3 hours by default and up to 72 hours on request.

[PayPal] Transaction cannot complete. error cause is unknown even to PayPal employees, so you have to contact credit card companies or banks

PayPal API Error 10417 Transaction cannot complete. — even PayPal cannot pinpoint the cause, so customers must contact their card issuer or bank.