I just installed WordPress 5.6 successfully on my Synology NAS in the /web root directory. After creating an ftp user, providing read/write access, enabling SFTP, setting port forwarding of 21 and 22 to 22 on the router and the provide the login credentials for the ftp user, the update starts but after some time the the following error occurs when update a theme: "update failes". In the debug log, the following entry can be found: "[25-Dec-2020 21:40:12 UTC] PHP Notice: Undefined offset: 1 in /volume1/web/wp-admin/includes/class-ftp-pure.php on line 78"