diff --git a/frontend/src/constants.ts b/frontend/src/constants.ts
index a5da189..1cc9373 100644
--- a/frontend/src/constants.ts
+++ b/frontend/src/constants.ts
@@ -1 +1,3 @@
+//  WebSocket protocol (RFC 6455) allows for the use of custom close codes in the range 4000-4999
+export const APP_ERROR_WEB_SOCKET_CODE = 4332;
 export const USER_CLOSE_WEB_SOCKET_CODE = 4333;
diff --git a/frontend/src/generateCode.ts b/frontend/src/generateCode.ts
index fc408bc..7fc34e7 100644
--- a/frontend/src/generateCode.ts
+++ b/frontend/src/generateCode.ts
@@ -1,6 +1,9 @@
 import toast from "react-hot-toast";
 import { WS_BACKEND_URL } from "./config";
-import { USER_CLOSE_WEB_SOCKET_CODE } from "./constants";
+import {
+  APP_ERROR_WEB_SOCKET_CODE,
+  USER_CLOSE_WEB_SOCKET_CODE,
+} from "./constants";
 import { FullGenerationSettings } from "./types";
 
 const ERROR_MESSAGE =
@@ -46,8 +49,12 @@ export function generateCode(
     if (event.code === USER_CLOSE_WEB_SOCKET_CODE) {
       toast.success(CANCEL_MESSAGE);
       onCancel();
+    } else if (event.code === APP_ERROR_WEB_SOCKET_CODE) {
+      console.error("Known server error", event);
+      onCancel();
     } else if (event.code !== 1000) {
-      console.error("WebSocket error code", event);
+      console.error("Unknown server or connection error", event);
+      toast.error(ERROR_MESSAGE);
       onCancel();
     } else {
       onComplete();