diff --git a/wecom-message-processor.js b/wecom-message-processor.js
index f8b73ad..88df410 100755
--- a/wecom-message-processor.js
+++ b/wecom-message-processor.js
@@ -579,6 +579,7 @@
       return { passiveReplyXml: initialReplyXml };
     } else {
       // Sync mode: Wait for reply and then send it as passive reply
+      logger.warn("WeCom Self-Built App: Missing corpId or corpSecret. Operating in Sync mode. Cannot send immediate '思考中...' reply and may timeout if AI takes longer than 5 seconds. Configure corpId and corpSecret to enable Async mode.");
             let capturedReplyXml = null;
             let fullText = "";
             let fullMediaUrl = "";