# Sync the database schema

In rare situations, the WordPress database schema might not match the schema expected by the applications or plugin. For example switching to multisite, and the wp\_users table is missing the spam and deleted colums

To fix this issue locally, **create a file in the *mu-plugins*** folder such as `mu-plugins/db-upgrade.php` with the following contents, and load the site:

```PHP
<?php
require_once ABSPATH . 'wp-admin/includes/schema.php';
require_once ABSPATH . 'wp-admin/includes/upgrade.php';
dbDelta( wp_get_db_schema( 'global' ) );
```

After the page is loaded the file can be deleted.