Before June 30th, 2018 PayPal is requiring all account users to update their browsers to remain compliant with new security standards. You will not be able to access your PayPal account after June 30th if your browser isn’t updated. Learn how to upgrade your browser.
How do I upgrade my PayPal SDK version for .NET?
Upgrading SDK versions allows you to use the new features that PayPal has added to our web services. You can find complete information on updating your SDK as well as sample code on GitHub.