diff --git a/datamodels/2.x/itop-portal-base/portal/public/js/toolbox.js b/datamodels/2.x/itop-portal-base/portal/public/js/toolbox.js
index f37c36c69..1d572dbda 100644
--- a/datamodels/2.x/itop-portal-base/portal/public/js/toolbox.js
+++ b/datamodels/2.x/itop-portal-base/portal/public/js/toolbox.js
@@ -106,7 +106,11 @@ var CombodoPortalToolbox = {
 		if (oOptions.base_modal.usage === 'clone')
 		{
 			oModalElem = oSelectorElem.clone();
-			oModalElem.attr('id', oOptions.id)
+
+			// Force modal to have an HTML ID, otherwise it can lead to complications, especially with the portal_leave_handle.js
+			// See N°3469
+			let sModalID = (oOptions.id !== null) ? oOptions.id : 'modal-with-generated-id-'+Date.now();
+			oModalElem.attr('id', sModalID)
 				.appendTo('body');
 		}
 		// - Get an existing modal in the DOM