PayPal subscription billing modification not working

Question

We are using PayPal Payments Standard (aka Website Payments Standard) for our users subscription billing system.

Users want to upgrade their subscription from monthly to yearly for example.

So I generated a new subscription button with the new subscription parameters on my website, then click goto Paypal form, I see the current and new subscription on paypal platform, fine : (the amounts and cycle duration are simple tests values to demonstrate the problem)

Then click on SAVE button but paypal give an error saying :

"Amount can only be increased by 20%"

Paypal think I am only changing the price but it is not true I am also changing the billing duration (from month to year).

Do you know if it is possible with Paypal or the only way is to cancel the current subscription and start a new one ? That would be so bad from paypal.
Thanks in advance for help.

Answer 1

根据PayPal API文档，该文档已内置于其系统中https://developer.paypal.com/docs/classic/paypal-payments-pro/integration-guide/WPRecurringPayments/#id086530108PM