I have a Osc website which is working fine for years. There have a Paypal checkout option for customer which can receive paypal from customer when they pay by card or directly from their paypal account. But recently, there seems to be a link error with the paypal check out, customer complain that they can not use the check out to pay even though they had paid in the same way before. I have tried myself and found everytime it turned to error message even payment from anther proper Paypal account. I have contacted to Paypal about this account, they said the account is fully active. So I think they might be some link or code error. I hope a fully skilled and experienced develop can give me some help regarding this issue.