Why did I get API error code 10411?

PayPal returned API error code 10411 - This Express Checkout session has expired. Token value is no longer valid.

The default lifetime of your Express Checkout token is three hours, and your payment wasn't completed within that time.

Check that you're performing a proper Express Checkout API call. For complete information about Express Checkout API calls, see How do I create a one-time payment with Express Checkout?