We had problem with our credit card processing app. It was developed 5 years ago, running on Windows server 2003.
Today, it can't connect to https://payflowpro.paypal.com
. I called Paypal, they're upgrading their card processing server from SHA-1 to SHA2. He suggested me to wait until the upgrade finishes and try again. If it doesn't, I have to follow the below documentation to make change to our card processing app connecting to their server.
Going through that, it seems, I just have to move the app from Windows 2003 to Windows 2012 in order to send authorization and charge with updated encryption? It doesn't say the app has to use new SDK, so I guess just moving the app from old Windows to new Windows OS would fix.
I'm not a developer, if it can be done in system job wise, I would do that.