diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
index 0b2d76bd38..d6ce4b1633 100644
--- a/doc/src/sgml/ref/pgupgrade.sgml
+++ b/doc/src/sgml/ref/pgupgrade.sgml
@@ -603,7 +603,8 @@ rsync --archive --delete --hard-links --size-only --no-inc-recursive /vol1/pg_tb
Configure the servers for log shipping. (You do not need to run
pg_start_backup() and pg_stop_backup()
or take a file system backup as the standbys are still synchronized
- with the primary.)
+ with the primary.) Replication slots are not copied and must
+ be recreated.