NVP API does not work in Sandbox paypal environment

Question

I have a site that is working perfectly since several months by implementing a expresscheckout based on NVP API Call.

I use both my own development user *-facilitator@xxx and the API credentials.

The fact is that I have not changed anything but since yesterday when I execute my call to the server https://api-3t.sandbox.paypal.com/nvp with the following string the server responses nothing.

USER=sdk-three_api1.sdk.com&PWD=QFZCWN5HZM8VBG7Q&SIGNATURE=A-IzJhZZjhg29XQ2qnhapuwxIDzyAZQ92FRP5dqBzVesOkzbdUONzmOU&VERSION=202&PAYMENTREQUEST_0_PAYMENTACTION=Sales&PAYMENTREQUEST_0_AMT=6&RETURNURL=https://www.alasediciones.com/detalles_pedido&CANCELURL=https://www.alasediciones.com/error&METHOD=SetExpressCheckout

What is it happening? What thing do I have to fix?

It is very strange.... Please, I need a solution because the next week y Company will be running.

Thank you

Answer 1

Paypal recently made a change to their sandbox environment a few days ago (Jan 19-20th 2016), requiring connections to the sandbox be done over TLS 1.2 and HTTP 1.1. Lots of people seem to be running into issues with this, including myself. Try making sure your code is making the request with the latest version of TLS (1.2), that seems to have worked for a lot of people.

Link to the change description on the PayPal blog:

https://devblog.paypal.com/upcoming-security-changes-notice/