diff --git a/htdocs/public/payment/newpayment.php b/htdocs/public/payment/newpayment.php
index b351367f6ea..0e24d94c177 100644
--- a/htdocs/public/payment/newpayment.php
+++ b/htdocs/public/payment/newpayment.php
@@ -376,9 +376,6 @@ if ($action == 'dopayment') {
 			dol_syslog("SCRIPT_URI: ".(empty($_SERVER["SCRIPT_URI"]) ? '' : $_SERVER["SCRIPT_URI"]), LOG_DEBUG); // If defined script uri must match domain of PAYPAL_API_OK and PAYPAL_API_KO
 
 			// A redirect is added if API call successfull
-			if ($source == 'conferencesubscription') {
-				$PAYPAL_API_OK .= '&invoice='.dol_encode($invoice->id, $dolibarr_main_instance_unique_id);
-			}
 			$mesg = print_paypal_redirect($PAYPAL_API_PRICE, $PAYPAL_API_DEVISE, $PAYPAL_PAYMENT_TYPE, $PAYPAL_API_OK, $PAYPAL_API_KO, $FULLTAG);
 
 			// If we are here, it means the Paypal redirect was not done, so we show error message
@@ -397,10 +394,6 @@ if ($action == 'dopayment') {
 		$urlok = preg_replace('/securekey=[^&]+/', '', $urlok);
 		$urlko = preg_replace('/securekey=[^&]+/', '', $urlko);
 
-		if ($source == 'conferencesubscription') {
-			$urlok .= '&invoice='.dol_encode($invoice->id, $dolibarr_main_instance_unique_id);
-		}
-
 		$mesg = '';
 		if (empty($PRICE) || !is_numeric($PRICE)) {
 			$mesg = $langs->trans("ErrorFieldRequired", $langs->transnoentitiesnoconv("Amount"));
@@ -755,9 +748,6 @@ if ($action == 'charge' && !empty($conf->stripe->enabled)) {
 		header("Location: ".$urlko);
 		exit;
 	} else {
-		if ($source == 'conferencesubscription') {
-			$urlok .= '&invoice='.dol_encode($invoice->id, $dolibarr_main_instance_unique_id);
-		}
 		header("Location: ".$urlok);
 		exit;
 	}
diff --git a/htdocs/public/payment/paymentok.php b/htdocs/public/payment/paymentok.php
index 3d3946927c8..1cfeb99ec80 100644
--- a/htdocs/public/payment/paymentok.php
+++ b/htdocs/public/payment/paymentok.php
@@ -104,7 +104,6 @@ if (empty($FULLTAG)) {
 }
 $source = GETPOST('s', 'alpha') ? GETPOST('s', 'alpha') : GETPOST('source', 'alpha');
 $ref = GETPOST('ref');
-$invoiceref = GETPOST('invoice');
 
 $suffix = GETPOST("suffix", 'aZ09');
 $membertypeid = GETPOST("membertypeid", 'int');