diff --git a/frontend/app.js b/frontend/app.js
index 40c1ec0..670d67d 100644
--- a/frontend/app.js
+++ b/frontend/app.js
@@ -3118,15 +3118,20 @@
       watcher_debounce: _getFieldNum("cfg-watcher-debounce", 2.0),
     };
     try {
-      await fetch("/api/config", {
+      const res = await fetch("/api/config", {
         method: "POST",
         headers: { "Content-Type": "application/json" },
         body: JSON.stringify(body),
       });
-      showToast("Configuration backend sauvegardée");
+      if (res.ok) {
+        showToast("Configuration backend sauvegardée", "success");
+      } else {
+        const errorData = await res.json().catch(() => ({}));
+        showToast(errorData.detail || "Erreur de sauvegarde", "error");
+      }
     } catch (err) {
       console.error("Failed to save backend config:", err);
-      showToast("Erreur de sauvegarde");
+      showToast("Erreur de sauvegarde", "error");
     }
   }