PayPal Sandbox 500 Proxy Error- PayPal Adaptive

Question

We are aware that PayPal rolling out upgrades to make use of SSL/TLS SHA256 for security purposes. Today i met with strange issue on PayPal Sandbox mode for my PayPal Adaptive Application even though my site follows HTTPS. To add further, same application works fine in Production(not sandbox).Please enlighten me, was this an issue in Application or Rollout issues? same issue reported in PayPal community but no response https://www.paypal-community.com/t5/About-Payments/Adaptive-payment-api-is-sending-Proxy-error/m-p/1091510

The proxy server could not handle the request AdaptivePayments/Pay
Reason: Error during SSL Handshake with remote server

07-27-2016 @ 13:43:35 - Error in generate payment key: Array
[headers] => Array
[date] => Wed, 27 Jul 2016 13:43:35 GMT
            [server] => Apache
            [connection] => close
            [http_x_pp_az_locator] => sandbox.slc
            [paypal-debug-id] => 8913861a40cd4
            [set-cookie] => Array
                (
                    [0] => X-PP-SILOVER=name%3DSANDBOX3.APIT.1%26silo_version%3D1880%26app%3Dadaptivepaymentspartaweb_api3t%26TIME%3D2277152855%26HTTP_X_PP_AZ_LOCATOR%3Dsandbox.slc; Expires=Wed, 27 Jul 2016 14:13:35 GMT; domain=.paypal.com; path=/; Secure; HttpOnly
                    [1] => X-PP-SILOVER=; Expires=Thu, 01 Jan 1970 00:00:01 GMT

[response] => Array
        (
            [code] => 500
            [message] => Proxy Error
        )

    [cookies] => Array
        (
            [0] => WP_Http_Cookie Object
                (
                    [name] => X-PP-SILOVER
                    [value] => name=SANDBOX3.APIT.1&silo_version=1880&app=adaptivepaymentspartaweb_api3t&TIME=2277152855&HTTP_X_PP_AZ_LOCATOR=sandbox.slc
                    [expires] => 1469628815
                    [path] => /
                    [domain] => .paypal.com
                    [secure] => 
                    [httponly] => 
                )

            [1] => WP_Http_Cookie Object
                (
                    [name] => X-PP-SILOVER
                    [value] => 
                    [expires] => 1
                    [path] => /AdaptivePayments/
                    [domain] => svcs.sandbox.paypal.com

Answer 1

Edit July 28th, 9:50am EDT: It appears the teams were able to track down what they believe to be the issue overnight, and released a code fix. Can you please verify that the problem has been fixed? I'll report back if that's not the case. Thanks.

We've had a few reports about failed requests on sandbox. I'm working with the sandbox and support teams internally in PayPal to figure out what's going on. Right now it looks like they're seeing the error responses and have teams on it to diagnose the problem. Just to note, this does look like it's restricted to sandbox and not any of the production servers. I'll post back when I hear more.