I am supporting eCommerce project that uses obsolete PayPal Adaptive Payments. This week Sandbox PayPal authorization window started redirecting to wrong URL after login. This wrong URL is https://www.sandbox3.paypal.com/us/cgi-bin/webscr?cmd=_ap-payment-ul&SESSION=<session>&dispatch=<dispatch>&mayflyId=<mayflyId>&flowType=AP_PAYMENT. As a result redirects fail. If manually delete this "3" in the address and send request, payment is executed properly. This issue was found using Sandbox.
Have you thoughts about it or even experience? Please, help or give advice!
P.S. I know that Adaptive Payments are obsolete, but I have no chance to recreate payments using new services right now.