So far so good, but even if it gets that far, there's still a chance of failure, as seen in this recent screenshot: The status message that appears just before "Installation Failed" explains what Word Press file.The name begins with a dot, so if you don't see it using your FTP program, try logging into your server's control panel and using the file manager to find and delete.
If you're able to upgrade via the Admin, updating your site(s) should be a piece of cake: just log in, click a few buttons, wait a few minutes, and done.
Proper file permissions are the key to smooth auto-Make sure that your entire wordpress directory is owned by the username under which your Apache server runs.
For example, if your server runs as https, and your files live in /var/wordpress do a "chown -R apache.apache /var/wordpress." (or CHMOD equivalent) and trying the auto-update again.
If an out-of-date plugin causes your upgrade to fail, you can usually delete the plugin code rather than uninstalling it from within Moodle so that the data associated with it is not deleted.
Before you begin upgrading your site, you should put it into maintenance mode to stop any non-admin users from logging in.