I'm getting this error today when I try to check out using PayPal — and more importantly, so are my customers. Going straight from the shopping cart to the yellow PayPal Express button seems to be working, but clicking "Checkout" and selecting PayPal on step 2 of 3 results in "PayPal Express Checkout failed. Please contact store for more information." Interestingly enough, in performing the same steps just yesterday, this error didn't occur, but I haven't changed any payment settings. I don't know where to begin. What causes this error?

In just the past couple of days, we're seeing all these PayPal errors:

I revisted the source code of this part and still couldn't figure out what caused this.

Any progress? From looking at the Event Log, it appears we're losing out on more sales than we're completing right now:

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Source Description Date
Attempt to Start PayPal Checkout Failed
Method Call on PayPal API SetExpressCheckout Failed. Detailed Information will follow.
8/1/2008 3:05:20 PM
PayPal Express Checkout Error
Error Number:10471 Error Message:ReturnURL is invalid. Parameter Payment Amount:29.97000000000000000000 Parameter Return Url:/12OffGiftCertificates/ShoppingCart/tabid/152/CheckoutMode/1/Control/Checkout/Default.aspx Parameter Cancel Url:/12OffGiftCertificates/ShoppingCart/tabid/152/Control/Checkout/Default.aspx
8/1/2008 3:05:20 PM
PayPal Express Checkout Failed
No specific error message has been recorded in system.
8/1/2008 3:05:20 PM
PayPal Express Checkout Error
Error Number:10472 Error Message:CancelURL is invalid. Parameter Payment Amount:29.97000000000000000000 Parameter Return Url:/12OffGiftCertificates/ShoppingCart/tabid/152/CheckoutMode/1/Control/Checkout/Default.aspx Parameter Cancel Url:/12OffGiftCertificates/ShoppingCart/tabid/152/Control/Checkout/Default.aspx
8/1/2008 3:05:20 PM
Attempt to Start PayPal Checkout Failed
Method Call on PayPal API SetExpressCheckout Failed. Detailed Information will follow.
8/1/2008 3:04:53 PM
PayPal Express Checkout Error
Error Number:10471 Error Message:ReturnURL is invalid. Parameter Payment Amount:29.97000000000000000000 Parameter Return Url:/12OffGiftCertificates/ShoppingCart/tabid/152/CheckoutMode/1/Control/Checkout/Default.aspx Parameter Cancel Url:/12OffGiftCertificates/ShoppingCart/tabid/152/Control/Checkout/Default.aspx
8/1/2008 3:04:53 PM
PayPal Express Checkout Error
Error Number:10472 Error Message:CancelURL is invalid. Parameter Payment Amount:29.97000000000000000000 Parameter Return Url:/12OffGiftCertificates/ShoppingCart/tabid/152/CheckoutMode/1/Control/Checkout/Default.aspx Parameter Cancel Url:/12OffGiftCertificates/ShoppingCart/tabid/152/Control/Checkout/Default.aspx
8/1/2008 3:04:53 PM
PayPal Express Checkout Failed
No specific error message has been recorded in system.
8/1/2008 3:04:53 PM
PayPal Express Checkout Failed
No specific error message has been recorded in system.
8/1/2008 3:04:40 PM
PayPal Express Checkout Error
Error Number:10471 Error Message:ReturnURL is invalid. Parameter Payment Amount:29.97000000000000000000 Parameter Return Url:/12OffGiftCertificates/ShoppingCart/tabid/152/CheckoutMode/1/Control/Checkout/Default.aspx Parameter Cancel Url:/12OffGiftCertificates/ShoppingCart/tabid/152/Control/Checkout/Default.aspx
8/1/2008 3:04:40 PM

This goes on for over 100 entries for August 1st alone. On that date, we had only three successful sales. Since no one on earth would repeat the same steps to see the same error 100 times for a single purchase, I am guessing we missed anywhere between 50 and 100 sales that day. Although your customer service has been exemplary in most other matters, and we want to continue to support the project, we will have no choice but to abandon our efforts and start fresh with a new ecommerce system unless this can be fixed immediately.

Okay... this is rather urgent, so would it not be simpler to tell PayPal to expect data from sundaypaper.com? Is that a setting in the admin somewhere?

Howard Landsman wrote Okay... this is rather urgent, so would it not be simpler to tell PayPal to expect data from sundaypaper.com? Is that a setting in the admin somewhere?

Unfortunately PayPal API doesn't support such setting as far as I know.