diff --git a/clientv3/watch.go b/clientv3/watch.go
index cfa478126..91e6db26a 100644
--- a/clientv3/watch.go
+++ b/clientv3/watch.go
@@ -762,6 +762,8 @@ func (w *watchGrpcStream) joinSubstreams() {
 }
 
 // openWatchClient retries opening a watch client until success or halt.
+// manually retry in case "ws==nil && err==nil"
+// TODO: remove FailFast=false
 func (w *watchGrpcStream) openWatchClient() (ws pb.Watch_WatchClient, err error) {
 	for {
 		select {