I have Upgraded Magento from 1.4 To 126.96.36.199, Previously on site PayPal Standard was working fine. I have again entered the merchant email, Set Payment Action to "Sale", Set Enable SSL verification to "No".
But After Clicking Pay Now button on PayPal I am getting the following error:
Return to merchant and try a different payment method. We are not able to process your payment using your PayPal account at this time. Please return to the merchant's website and try using a different payment method (if available).
I have enabled the debug mode to Yes. But log file also not created. I have checked the permission too.