Gateway Callback - Problem with Redirect after addInvoicePayment

[AroundTheCorner]

I am having a problem with a Redirect after a succesful payment in the Callback file.

If I put a header("Location: $url")

addInvoicePayment()- function, is ignored.

If I put it in front, the redirect works just fine.

I checked the addInvoicePayment and it returns true, so I assume there are no errors, only that there is no redirect.

Anyone has a tip on how to debug/find a solution?

if ($success) {
	addInvoicePayment($invoiceId,$transactionId,$paymentAmount,$paymentFee,$gatewayParams['name']);
	header("Location: ".$CONFIG['SystemURL']."/viewinvoice.php?id=$invoiceId&paymentsuccess=true");
	exit();
}

 

header location on top of addInvoice() works fine (I am aware the flow below makes no sense!).

if ($success) {
	header("Location: ".$CONFIG['SystemURL']."/viewinvoice.php?id=$invoiceId&paymentsuccess=true");
	exit();	
	addInvoicePayment($invoiceId,$transactionId,$paymentAmount,$paymentFee,$gatewayParams['name']);
}

Tested on Php7.4& Whmcs 8.2
Php 8.1 & whmcs 8.8

 

Thank you for any hints/suggestions.