diff --git a/README.md b/README.md
index 1b56d27..157227c 100644
--- a/README.md
+++ b/README.md
@@ -7,3 +7,21 @@
 mkdir data/data
 chown www-data data/data
 ```
+
+## troubleshooting
+
+
+### mariadb update
+
+message:
+
+```
+[Warning] InnoDB: Table mysql/innodb_table_stats has length mismatch in the column name table_name. Please run mysql_upgrade
+```
+
+solution:
+
+```
+source nextcloud.conf
+docker-compose exec nextcloud-database sh -c 'mysql_upgrade -uroot -p${NEXTCLOUD_DATABASE_ROOT}'
+```