diff --git a/back/methods/osticket/closeTicket.js b/back/methods/osticket/closeTicket.js
index c2f6aab1e..601470a02 100644
--- a/back/methods/osticket/closeTicket.js
+++ b/back/methods/osticket/closeTicket.js
@@ -121,8 +121,8 @@ module.exports = Self => {
                     };
                     await fetch(ostUri, params);
                 } catch (e) {
-                    const err = new Error(`${ticketId} Ticket close failed: ${e.message}`);
-                    err.stack += e.stack;
+                    const err = new Error(`$s{ticketId} Ticket close failed: ${e.message}`);
+                    err.stack = e.stack;
                     console.error(err);
                 }
             }