Upgrade Debian

1. Make Backup

# dd if=/dev/sda of=/dev/sdb bs=4096

2. Current version check

cat /etc/debian_version

or

lsb_release -a

3. Install screen app

To prevent ssh problems, install screen:

sudo apt install screen

4. screen quick help

Start screen: screen

Exit: exit

Reconnect: screen -r

5. Select new version of debian

It's recommended to upgrade +1 version, e.g.: 10 > 11, 11 > 12 etc

6. Update current Debian

sudo apt update

sudo apt upgrade

sudo apt dist-upgrade

sudo apt --purge autoremove

7. Change 'codename' in sources.list files

/etc/apt/sources.list

/etc/apt/sources.list.d/*

8. Perform upgrade

sudo apt update

sudo apt upgrade

sudo apt dist-upgrade

sudo apt --purge autoremove

9. See also:

Команда dd и все что с ней связано, habr.com

https://support.hitex.by/index.php?/Knowledgebase/Article/View/kak-obnovit-debian-so-staroi-versii-do-bolee-novoi

Debian versions, debian.org