diff --git a/FAQ.md b/FAQ.md
index ea2a3f7..9865546 100644
--- a/FAQ.md
+++ b/FAQ.md
@@ -316,6 +316,7 @@ https://github.com/rustdesk/rustdesk/discussions/6398#discussioncomment-9065991
 - Check your relay server (hbbr/21117) is using the same key as hbbs (using the same `id_ed25519` file or having the same content). You can see some errors related to connection to relay server in https://github.com/rustdesk/rustdesk/wiki/FAQ#access-logs on controlled side.
 
   It may be caused by using wrong volumns mapping in docker compose file, please strictly follow https://rustdesk.com/docs/en/self-host/rustdesk-server-pro/installscript/docker/#docker-compose, or you changed hbbs key but forgot to sync to hbbr (and restart), or some other reasons.
+ > We have seen two cases having this hbbr key issue while upgading RustDesk server.