Why does Adyen Alipay (test env) url show ILLEGAL_SIGN error?
I've been attempting to integrate with Adyen and was successful on some of the payment methods like Diners, JCB, Unionpay. However for Alipay, I've been getting this ILLEGAL_SIGN sign error and I can't find anything in the documentation related to this. Following this documentation: https://docs.adyen.com/payment-methods/alipay/api-only, on /payments call, Adyen will return a url. After going to this url, a page with ILLEGAL_SIGN error is shown. What could have caused this?
I tried Adyen's sample rails app (https://github.com/adyen-examples/adyen-rails-online-payments). In this sample app, the other payments are ok but for Alipay it also gets this ILLEGAL_SIGN error.
Adyen sandbox pages are not maintained by them, therefore it is quite likely that there is something between Adyen and Alipay that is causing this problem. I would just contact their support and ask them to take a look to it.