diff --git a/js/forms-json-utils.js b/js/forms-json-utils.js
index 84ed4904b..92b8b3a97 100644
--- a/js/forms-json-utils.js
+++ b/js/forms-json-utils.js
@@ -112,13 +112,14 @@ function OnUnload(sTransactionId, sObjClass, iObjKey, sToken)
 	if (!window.bInSubmit)
 	{
 		// If it's not a submit, then it's a "cancel" (Pressing the Cancel button, closing the window, using the back button...)
-		// IMPORTANT: the ajax request MUST BE synchronous to be executed in this context
-		$.ajax({
-			url: GetAbsoluteUrlAppRoot()+'pages/ajax.render.php',
-			async: false,
-			method: 'POST',
-			data: {operation: 'on_form_cancel', transaction_id: sTransactionId, obj_class: sObjClass, obj_key: iObjKey, token: sToken }
-		});
+		var sUrl = GetAbsoluteUrlAppRoot()+'pages/ajax.render.php';
+		var oFormData = new FormData();
+		oFormData.append('operation', 'on_form_cancel');
+		oFormData.append('transaction_id', sTransactionId);
+		oFormData.append('obj_class', sObjClass);
+		oFormData.append('obj_key', iObjKey);
+		oFormData.append('token', sToken);
+		navigator.sendBeacon(sUrl, oFormData);
 	}
 }