diff --git a/manual/upgrade/upgrade_docker.md b/manual/upgrade/upgrade_docker.md
index 67242466..2caacea9 100644
--- a/manual/upgrade/upgrade_docker.md
+++ b/manual/upgrade/upgrade_docker.md
@@ -9,6 +9,8 @@ Please check the **upgrade notes** for any special configuration or changes befo
 
 ## Upgrade from 11.0 to 12.0
 
+Note: If you have a large number of `Activity` in MySQL, clear this table first [Clean Database](../administration/clean_database). Otherwise, the database upgrade will take a long time.
+
 From Seafile Docker 12.0, we recommend that you use `.env` and `seafile-server.yml` files for configuration.
 
 ### Backup the original docker-compose.yml file:
diff --git a/manual/upgrade/upgrade_notes_for_12.0.x.md b/manual/upgrade/upgrade_notes_for_12.0.x.md
index 49a093d6..6aed8f69 100644
--- a/manual/upgrade/upgrade_notes_for_12.0.x.md
+++ b/manual/upgrade/upgrade_notes_for_12.0.x.md
@@ -80,6 +80,8 @@ The following instruction is for binary package based installation. If you use D
     docker compose restart
     ```
 
+Note: If you have a large number of `Activity` in MySQL, clear this table first [Clean Database](../administration/clean_database). Otherwise, the database upgrade will take a long time.
+
 ### 1) Stop Seafile-11.0.x server
 
 ### 2) Start from Seafile 12.0.x, run the script