Paypal has been working fine for user upgrades for 6 months. I have not changed abything in the xenforo Payment gateway setup (it is the same account email it has always been), nor have I changed anything in paypal. But I have got this warning from paypal: Please check your server that handles PayPal Instant Payment Notifications (IPN). Instant Payment Notifications sent to the following URL(s) are failing: http://cafesaxophone.com/payment_gateway.php?method=paypal If you do not recognize this URL, you may be using a service provider that is using IPN on your behalf. Please contact your service provider with the above information. If this problem continues, IPNs may be disabled for your account. Thank you for your prompt attention to this issue. However in paypal I have the IPN set as in the xenforo instructions: You should enter a notification URL of [your Board URL]/payment_callback.php. Can anyone help please?