Hi,
I have followed the instructions and replaced the extension files but the problem is still the same. perhaps it is a different problem. I have recently installed Abantecart version 1.3.4 and have installed the Paypal commerce extension and activated  'ON'. On clicking on the edit button and then the Paypal Get Started the following message comes up: Oops, something went wrong. Please try a bit later. Can you please advise how to proceed. Thank you