Is PayPal having problems? In my last 2 orders, the customers opted for PayPal
onsite, but because this apparently did not work, the Shipping Method says: Request
for invoice (backup method)
Are others also having this problem at the moment?
Try disconnecting your PayPal and reconnecting it
How do you disconnect it? I tried closing all sessions on my PayPal account and
then log in during checkout, but I still receive this error. I know nothing is
wrong on my side because a friend couldn't place an order either and I've
paid in 3 different places today without any problem.