Debian Bullseye: upgrade from Debian Buster XFCE

 

Edit /etc/apt/sources.list

# main security
deb https://security.debian.org/debian-security bullseye-security/updates main
#deb-src https://security.debian.org/debian-security bullseye-security/updates main

# main mirror Indonesia
deb http://kebo.pens.ac.id/debian bullseye main
deb http://kebo.pens.ac.id/debian bullseye-updates main

# NON FREE
deb https://deb.debian.org/debian bullseye main contrib non-free

# BACKPORTS
deb https://deb.debian.org/debian bullseye-backports main

Update without new packages

# apt upgrade --without-new-pkgs

During upgrade, you need to restart some services.

Restart, open root terminal and make full upgrade (required more than 800MB)

# apt full-upgrade

Restart your PC.

Clean up unused installer

# apt-get autoclean && apt-get autoremove -y

If you get trouble connecting to internet (can not resolve servername) after upgrading edit /etc/resolv.conf

search 8.8.8.8 1.1.1.1
nameserver 127.0.0.1
nameserver 8.8.8.8
nameserver 1.1.1.1

Restart your networking

# systemctl restart networking

If you install dnsmasq and get trouble connecting to internet (can not resolve servername) after upgrading, edit /etc/dnsmasq.conf

#no-resolv
# dedetok 2021-08-18
no-resolv
server=8.8.8.8
server=1.1.1.1

Reboot