Paypal Checkout Signature Verification Failed

[Thatguyownzz]

Hi all, 
i was previously on a previous version to whmcs and was dealing with a error anytime a customer went to checkout with paypal. 
after applying hotfix's and upgrading to the newest version of whmcs those issues are not present. 
But now i get the error Paypal Webhook Signature verification failed. On loads of payments, i have removed and re-linked the billing panel to paypal API but seems the issues not going away. 
payments are being taken but billing system is not applying them to invoices resorting in a lot of manual adding transactions to invoices
i have checked Hotfixs for this issue 

[vicki love]

did you ever find the answer? I'm having the same problem 

 

[nestitepsu]

a bit late, but here is the answer to this problem:

"Signature Verification Failed

Signature Verification Failed indicates a problem in the payment notification anti-spoof verification. When a payment notification is received from PayPal, WHMCS makes an API request to PayPal confirming that the notification originated from PayPal.

Seeing this typically indicates that a subscription renewal payment was made through a different integration app from the one currently linked to your WHMCS installation.

This situation can arise if Unlink PayPal Account on the module configuration was used after the PayPal subscription was originally created. Once the unlink function is used, the subscription payments that pre-date it can no longer be recorded in WHMCS. Such subscriptions will need to be cancelled via the PayPal website. Clients can then create a new subscription under the current integration app linked to your WHMCS installation when their next invoice is due."

source: PayPal Checkout - WHMCS Documentation