Troubleshooting PayPal IPN Failure Emails
Whilst operating WHMCS version 8.0 or 8.1 and using the PayPal module, an automated notification email may be received from PayPal with information of IPN failures:
Please check your server that handles PayPal Instant Payment Notifications (IPN). IPNs sent to the following URL(s) are failing:
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.
The URL listed is a directory name. This article does not apply if a full file path is listed
Payment notifications using an older PayPal Basic module are being sent for payments made via a newer PayPal module.
The newer PayPal module does not utilize IPNs, meaning these notifications are surplus to requirements. The URL reporting the failures must return a 200 HTTP response, which is not the case when used in conjunction with the Default to Client Area option.
Update to WHMCS 8.4.0 or above via the Utilities > Update WHMCS page.
CORE-17221 - Prevent redirection loop for invalid CSRF checks in client area