diff --git a/front/lib/api/assistant/messages.ts b/front/lib/api/assistant/messages.ts
index 2ddf2fc32868..61e4b36f7d15 100644
--- a/front/lib/api/assistant/messages.ts
+++ b/front/lib/api/assistant/messages.ts
@@ -416,7 +416,7 @@ export async function fetchConversationMessages(
   });
 
   if (!conversation) {
-    return new Err(new Error("Conversation not found."));
+    return new Err(new ConversationError("conversation_not_found"));
   }
 
   const { hasMore, messages } = await fetchMessagesForPage(